SHORTER ARTICLES AND DISCUSSION 



TRICHOMONAS AND BLACKHEAD IN TURKEYS 



In reading the introduction to Dr. E. E. Tyzzer 's contribu- 

 tion in the May issue of the Journal of Medical Research entitled 

 "Developmental Stages of the Protozoon of 'Blackhead' in 

 Turkeys." one is almost certain to be left with the impression 

 that the conception of the agency of the common flagellate, 

 Trichomonas, in producing pathological conditions character- 

 istic of blackhead in turkeys, as described in several papers by 

 the present writer, has no legs to go on, and would scarcely 

 receive the consideration of sane protozoologists. Of course this 

 is not the impression that Dr. Tyzzer meant to leave; so that it 

 is fortunate that, in the experimental section of the paper re- 

 ferred to, he makes certain observations which are more favor- 

 able to the "flagellate hypothesis." Fearing, however, lest the 

 hypothesis of tissue-invasion by Trichomonas might as yet be 

 too frail to survive long under the criticism of two such men as 

 Dr. Tyzzer and Dr. Theobald Smith (formerly chief proponent 

 of the "Amebic theory"), the present writer, who first had the 

 misfortune seriously to mention Trichomonas in connection with 

 blackhead, wishes to point out a few instances in which Dr. Tyz- 

 zer's criticisms, real or implied, are due either to careless read- 

 ing of the original papers, or to a too hurried examination of the 

 plates, or to both. 



In way of introduction it may be said that Dr. Smith's first 

 exposition of the blackhead disease, together with his original 

 description of the causative agent, Amcha mclcagrirfis, appeared 

 in 1895. It is true that, at that time, as Dr. Tyzzer states, the 

 possibility of the relationship between Ameba melcacir'oli* and 

 the flagellates was suggested by Dr. Smith. And the suggestion 

 was expressed in these words : 



There is probably no genetic relation between this hypothetical organ- 

 ism (flagellate) and the true parasite of the disease under consideration. 



For twenty years the "Ameba hypothesis" stood; and it was 

 not until this interpretation was called into question by Cole and 

 the present writer that (as Dr. Tyzzer states), Dr. Smith ex- 

 plained "that the name 'Ameba' is employed tentatively, and 

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