we have either not furnished it suitable food or are unac- 1 QQ 

 quainted with some physical factor which influences its metab- 

 olism." It was such broad philosophy that underlay all his 

 work. He had been studying the total parasitic inhabitants of 

 the mouth but was after the protozoal types more specifically. 

 "Quite a series of attempts" with media of different com- 

 position yielded him nothing. Now he found one that fur- 

 nished the "suitable food" called for in the above equation. 

 It was modification of a medium recommended by W Blair 

 M Martin. Wherry said he had "been particularly impressed 

 with his work." It consisted of agar-agar (Japanese seaweed 

 jelly) mixed with sodium phosphate and "rich in ovomucoid" 

 — nothing far removed from the eternal egg diet upon which 

 Wherry had so often and so long fed his own stock. To it he 

 had added the fluid which collects over the lung in pleurisy, 

 allowing the mixture to "solidify in the slanting position for a 

 night," as is the custom of bacteriologists; whereafter, he 

 permitted "the water of syneresis to collect for a day longer." 

 (This reference to "water of syneresis" bears noting. The 

 bacteriologists had long called it "water of condensation," 

 which it is not. Wherry gave the matter right explanation — a 

 fluid squeezed off by the more solid hydrophilic colloid. ) 



On this substratum the Entamoeba buccalis "survived." So 

 did another protozoon never before cultivated, and found in 

 dirty mouths and on other mucous surfaces, Trichomonas 

 intestinalis. But they did more than this — they grew. It was 

 particularly noticeable in "the water of syneresis." In this 

 Wherry found the second element of his equation, that "phys- 

 ical factor which influences metabolism." It was all a matter 

 of correct oxygen pressure. Said he of his experiments: "The 

 protozoa grow best under aerobic conditions, while the bac- 

 terial flora is almost entirely anaerobic." The startling appli- 

 cation to the problem of bacterial culture which he was to 

 make of this generalization was to come forth shortly. In the 

 meantime he deprived his Entamoeba of air by sealing it under 

 a cover glass. In half an hour it went slimy and passed into 

 "a morphologic type such as one most frequently encounters 

 in preparations direct from the gums." Infection of host, in 

 other words, was infection under "anaerobic" conditions and 



