Dates: b. 1871; 1898 to Geneva; 1913 to Illinois; death announcement in ASM NEWS 29:1, Jan., 1963
Locations: Assistant Bacteriologist, Wisconsin State Agricultural Experiment Station and the University of Wisconsin; Chair of Bacteriology, and Bacteriologist, New York Agricultural Experiment Station and Cornell (1899‑1913); Bacteriologist, University of Illinois Agricultural Experiment Station (1913‑); Prof. and Head, Dept. of Dairy Husbandry, Univ. of Illinois (1913‑1921); Chief, Dairy Research Bureau, The Frederick C. Mathews Co., Detroit (1922‑1940's)
Training: BS Wisc. 1896; MS Wisc. under Russell 1898; to Europe in 1898; PhD from Cornell 1910 on Classification
Fields: dairy; agricultural; food; plant pathology; BACT-NOM; soil; milk
Publications: thesis on silage; in Russell 1921 volume, "The Development of City Milk Supply Problems."; Harding and L.A. Rogers "The Efficiency of a Continuous Pasteurizer at Different Temperatures," BNYAES no. 172 (1899): 509‑530; Harding, Smith and Rogers, "Notes on Some Dairy Troubles," BNYAES no. 183 (1900): 175‑193; Harding, L.L. Van Slyke and E.B. Hart, "A Study of Enzymes in Cheese," BNYAES no. 203 (1901): 216‑244; Harding and Smith, "Control of Rusty Spot in Cheese Factories," BNYAES no. 225 (1902): 303‑329; Harding and F.C. Stewart, "Combating the Black Rot of Cabbage by the Removal of Affected Leaves," BNYAES no. 232 (1903): 43‑65; "The Role of Lactic‑Acid Bacteria in the Manufacture and in the Early Stages of Ripening of Cheddar Cheese," BNYAES no. 237 (1903): 165‑180; Harding and J.F. Nicholson, "A Swelling of Canned Peas Accompanied by a Malodorous Decomposition," BNYAES no. 249 (1904): 155‑168; Harding, F.C. Stewart and Prucha, "Vitality of the Cabbage Black Rot Germ on Cabbage Seed," BNYAES no. 251 (1904): 179‑194; Harding and Prucha, "The Quality of Commercial Cultures for Legumes," BNYAES no. 270 (1905): 347‑385; Harding, Smith and Moore, "The Bang Method of Controlling Tuberculosis, with an Illustration of its Application," BNYAES no. 277 (1906): 83‑190; Prucha and Harding, "Quality of Commercial Cultures for Legumes in 1906," Bull. NY Agr. Exp. Sta. no. 282 (1906): 274‑279; Harding and Wilson, "Inoculation as a Factor in Growing Alfalfa," BNYAES no. 300 (1908): 139‑164; Harding and Wilson, "Inoculation and Lime as Factors in growing Alfalfa," Bull. NY Agr. Exp. Sta. no. 313 (1909): 53‑75;
More Pubs: Harding, Wilson and George Smith, "Milking Machines: Effect of Method of Handling on Germ Content of the Milk," Bull. NY Agr. Exp. Sta. no. 317 (1909): 254‑292; Harding, Wilson, and George A. Smith, "The Modern Milk Pail," Bull. N.Y. Agr. Exp. Sta. no. 326 (1910): 249‑281; Harding and Prucha, "The Bacterial Flora of Cheddar Cheese," Tech. Bull. NY Agr. Exp. Sta. no. 8 (1908); Harding and Wilson, "Inoculation and Lime as Factors in growing Alfalfa," Bull. NY Agr. Exp. Sta. no. 313 (1909): 53‑75; Harding, Smith and Wilson, "Milking Machines: Effect of Method of Handling on the Germ Content of Milk," BNYAES no. 317 (1909): 254‑292; "The Constancy of Certain Physiological Characters in the Classification of Bacteria..." Technical Bulletin of the NYAES no. 13 (1910): 1‑41; Harding, Smith and Wilson, "The Modern Milk Pail," BNYAES no. 326 (1910): 249‑281; "Publicity and Payment Based on Quality as Factors in Improving a City Milk Supply," BNYAES no. 337 (1911): 80‑114; Harding, Reuhle, Wilson and Smith, "The Effect of Certain Dairy Operations Upon the Germ Content of Milk," BNYAES no. 365 (1913): 197‑233; with J.D. Brew, "The Financial Stimulus in City Milk Production," BNYAES no. 363 (1913): 165‑178; Harding and Wilson, "A Study of the Udder Flora of Cows," Tech. Bull. NY Agr. Exp. Sta. no. 27 (1913); "What is Meant by "Quality" in Milk?" Circular of the University of Illinois Agricultural Experiment Station no. 205 (1917): 1‑16; with Prucha, "An Epidemic of Ropy Milk," BUIAES no. 223 (1920): 109‑124; with Prucha, " Elimination of Germs from Dairy Utensils," BUIAES no 23 (1920): 137‑168; "Effect of Temperature of Pasteurization on the Creaming Ability of Milk," BUIAES no. 237 (1921): 393‑408; with Prucha, "Germ Content of Milk," BUIAES no. 236 (1921): 361‑391.
SAB Involvement: Charter member of the SAB; Added to SAB Comm. on Methods of Identification of Species 1910‑; Member Comm. on the Society's Classification Card 1916; SAB council member 1913; Member, Comm. on the Chart for Identification of Bacterial Species late 1910's; attended 1925 SAB meeting;
Archive Files: "Early Bacteriology," Harding, ca. 1938, from regional history folder, 7‑IIA, 10.16; H.A. Harding, Detroit, to Barnett Cohen, Baltimore, 27 February 1940, 3 pp., 7‑IIA, 9.12
In a 29 page autobiographical account, Harding recalls that he was drawn to medicine after declining training in the ministry. He enrolled at the Univ. of Wisconsin, intending 2 years of study before applying for the Rush Medical College. Harding's account mentions the difficulty he experienced trying to reconcile evolutionary theory with his faith, but draws no inference to the place of bacteriology in this debate.
Harding recalls that in 1892, Birge and Barnes taught a biology course which turned on the issue of complexity and evolution. "Bacteria and yeast cells were indicated as the approximate point at which the lines of plants and animals separated. We had yeast in our laboratory work, but coming at the beginning, before skill with the microscope had been acquired, I got only a vague idea of the structure of yeast cells." (7)
As an undergraduate, he was employed as a janitor to the Science Hall. In 1893‑1894, Harding prepared the media used for bacteriological work, for both faculty and students. His thesis was on silage, in the summer of 1895. He found that germ life is "commonly abundant in the material while silage is being formed, however, silage without intervention of germ life is a possibility, inasmuch as good silage developed in a saturated atmosphere of sulphuric ether." (Harding 1938, p. 24) He isolated a white colony producing rod forms, but owing to its high temperature of growth could not plate it on agar.
He spent the summers on botanical surveys of the North Wisconsin. Returning to graduate studies in 1896, Harding decided not to concentrate on dairy bacteria at such an early date, and worked on pathogenic and water bacteria.
At the 1899 meeting of the SAB, Harding presented two papers: "On the Use of Steam for Sterilization," and "On the Utility of the Supply of Live Steam in the Laboratory." This same title was repeated, with an abstract in the 1900 meeting. Harding was not present, so the paper was read by Ward, and discussed by Conn, Park, Abbot, Hill and Prescott.
At the 1901 meeting, Harding and Rogers presented on "Rusty Spot in Cheddar Cheese," in which they isolated Bacillus rudensis. This study of a cheese fault followed the model of medical bacteriology, as they isolated the suspected organism, inoculated a sterile vat of milk, reproduced the "diseased" condition, and recovered the same organism. They even suggest steam as a means of eliminating the bacillus. This was truly isolate, identify and kill.
At the 1904 SAB meeting, Harding and Prucha reported on "The Resistance of Pseudomonas campestris to Desiccation." The Ps. campestris was a plant pathogen, and this might have the first such paper at the SAB. They conclude that the organism could survive long periods. "At a time when so much stress is being laid upon the quickness with which pathogenic organisms are destroyed in nature these observations should tend to check hasty generalizations." The paper was discussed by Conn, Rosenau, Houghton and Duckwall, then published in Centralbl. f. Backt. Harding also presented a technical paper, "Some Experiences with Test‑Tubes," at the same meeting, which was discussed by Rickards, Houghton, Novy, Rosenau and Bergey.
At the 1905 SAB meeting, Harding and Prucha evaluated "Absorbent Cotton as a Medium for Distributing Pseudomonas radicicola." Apparently, there were a number of "failures" with cotton inoculants, in contrast with the germs shipped in soil. Like Chester, they suggested that the organisms did not survive desiccation. Also at the 1905 meeting, Harding and Prucha reported on a joint research project between the Botany Dept. of the Univ. of VT, and the Geneva Station on the group of organisms responsible for soft rot of vegetables. The paper is mostly technical, and was titled, "Variations in Gas Production by Bacteria Producing Soft Rot in Vegetables." It did have some implications for taxonomy.
Harding and Prucha returned in 1906 SAB meeting to discuss "Commercial Cultures of Pseudomonas radicicola," in which they discuss the commercial company practice of placing the cultures in metal containers, thus avoiding the problems of desiccation. They examined 14 cultures, finding them just as worthless. Kellerman commented.
At the 1908 meeting of the SAB, Harding and Prucha evaluated "The Utility of the Society's Card in Classifying the Cheese Flora." This article compares the card with Conn's botanical classification, and favors strongly the card. At the 1909 SAB Boston meeting, Harding and Morse used "The Society Card as a Basis for Classifying the Bacteria Producing Soft Rot in Vegetables." They concluded that the handful of separately described organisms were in fact identical in "all cultural characters except" gas formation, and that character was an artifact of poor fermentation tubes. The paper was discussed by Jackson and Winslow.
And, at the same 1909 meeting, Harding inquired "Does the Group Number on the Society Card Carry the Classification far enough to break up the Species?" Harding's studies involved P. campestris, a well known chromogenic plant pathogen whose "limits of the species can be determined with the minimum chance of error." He found with tests on several strains, there was no variation in the group number, save reduction of nitrates. This paper was discussed by Winslow, Esten and Harris.
Harding and Wilson reported on their work with regard to milk hygiene at the 1910 Ithaca SAB meeting, in a paper entitled the "Relation of Form of Milk Pail to Germ Content." They admit that many improved pails had been suggested, but few were used widely, rejected due to their excessive height or restrictive opening. Harding and Wilson also evaluated a "Method of Keeping Bacteria from Growing Plants." At the same meeting, Harding delivered a scathing attack on quantitative tests, in "What is the Value of Quantitative Bacteriology Determinations in the Control of City Milk Supply?" He returned to this argument at the 1911 meeting, discussing "The Bacterial Improvement of a Milk Supply by other than Laboratory Examinations." At the same 1911 meeting, Harding and Wilson reported on their research concerning "Udder Flora."
Ruehle and Harding presented, at the 1912 meeting, a technical "Comparison of Two Methods for Bacterial Analysis of Air." Harding himself discussed "Problems in Sanitary Dairy Inspection," in which he affords himself a few metaphorical liberties. "Milk resembles the human race in that its value is determined by two forces, its inheritance and its environment." Inheritance was the constituent of the milk, which of course meant that the environment could only worsen the genetic stock. Harding reiterated these claims at the 1913 meeting, with "Bacteria in Relation to the Public Milk Supply." Harding also returned to the "The Classification Card and the Type of Study which it Merits" at the 1913 meeting. Harding delivered the "Report of Committee on Revision of Society's Card," at the 1915 SAB meeting.
Harding repeated his stance on milk hygiene at the 1915 SAB meeting, with the "Relation of Bacteriology to City Milk Supplies." Harding maintained that "practically we have no method of determining the presence of such germs and protection must be sought through omnibus methods such as pasteurization..." With regard to counts as an indication of cleanliness, he argues that "as soon as the elements of time and temperature enter, such counts no longer indicate the character or extent of contamination." He concludes that standards, of any number, were mostly useless. Also at the 1915 SAB meeting, Ritte and Harding discussed "Statistical Examination of Data on Bacterial Counts." He returned to the SAB program in 1916, to report on the "Significance of Bacterial Counts in Judging Quality of Milk."
At the 1920 SAB meeting, Harding and Prucha submitted three papers: "Frequency of Ropy Milk Organisms in City Milk Supplies," "Destruction of Germ Life by Steam," and "Dirt as a Source of Germ Content in Milk." None of these appears in the minutes of the meeting, and probably were not delivered.
Harding supervised the session on "Systematic Bacteriology," and I believe delivered the Report of the Comm. on Revision of the Society's card.
At Geneva, Harding and Prucha studied the bacterial flora of Cheddar cheese, emphasizing new methods of cold curing and storage. A few years later, Harding studied the bacterial soft rot of certain vegetables.
Harding also recalls that in 1916, he was directed to develop a course in City Milk Supplies. That year, he again discussed "The Bacterial Count as an Index of Cleanliness in Milk" at the SAB meeting.
At Illinois, Harding and Prucha indicated that dairy utensils were the principal sources of contamination of milk, and later experiments demonstrated that bacterial counts were greatly reduced when clean utensils were disinfected with chlorine.
At the 1922 SAB meeting, Adams and Harding reported their "Test of Commercial Thionins for Staining Frost Little Plates." Harding, on his own, described "Some Factors Leading to Variation in the Bacterial Count of Pasteurized Milk." For the 1923 SAB meeting, Adams and Harding provided their "Observation on Thermophilic Bacteria in Milk from Farms." Also at the 1923 SAB meeting, Hungerford and Harding offered a paper on "The Influence of the Period of Operation of the Pasteurization upon the Bacterial Count of Milk." And, Harding and Archibald Ward discussed the "Thermophilic Bacteria in Composite Samples from Milk Plants."
Harding has a wonderful summary of dairy bacteriology in a letter to Cohen. He implies that it was Conn who first suggested using total bacterial counts as legal standards. "There was a period during which the bacterial plate count was taken as the most important available index of the desirability of milk supplies....It was maintained for a time that the bacterial plate count was markedly influenced by the physical cleanliness of the milk because the foreign matter getting into the milk carried germ life, sometimes in large quantities. Later studies showed that the amount of foreign matter getting into milk was so small that the germ life carried on such dirt was relatively unimportant....It was shown that there was no apparent coordination between the foreign matter in milk and its plate count." (2)
Conn himself showed that there was little correlation between the bacterial plate counts and the keeping qualities of milk.
As for the issue of bacterial flora in milk, "it was shown that there was no single temperature at which plates could be incubated to develop colonies of all various types of germ life common in milk." (3) Still, "plate counts had been clung to by milk supervising agencies because they lacked any other satisfactory test to cover safety." (3) The phosphatase tests slowly replaced plate counts.