October U, 1910] 



SCIENCE 



509 



Thomas M. Hills, Ph.B. (Wooster), and a 

 recent graduate student in the University of 

 Chicago, has been appointed assistant pro- 

 fessor of geology in the Ohio State University. 



Charles B. Wilson, Ph.D. (Hopkins), has 

 been appointed professor of biology at the 

 State Normal School, Westfield, Mass. 



DISCUSSION AND CORRESPONDENCE 



"^ AMCEBA MELEAGRIDIS 



To THE Editor of Science: Nearly two 

 years ago there appeared in this journal a com- 

 munication by Drs. L. J. Cole and P. B. Had- 

 ley,' concerning the etiology of a protozoan 

 disease of turkeys which demands some notice 

 on my part. 



The disease in question was investigated by 

 me in 1894 and described in detail in a bul- 

 letin of the Bureau of Animal Industry, U. S. 

 D'epartment of Agriculture which was pub- 

 lished in 1895. The disease is confined to the 

 two eseca and the liver. Minute round bodies 

 not more than 8-12ju, in diameter appear in 

 enormous numbers in the submucous and 

 intramuscular tissue of the walls of the caeca 

 and may extend even beyond these to the 

 mesenteries. In the liver there are circular 

 spots, representing partial necrosis of the liver 

 tissue and in these spots the same organisms 

 are also present in great numbers. This par- 

 asite I assumed to be an amcEba and called it 

 A. meleagridis. ■ The analogy between it and 

 human amoebiasis was very close. 



In the communication of Drs. Cole and 

 Hadley, my interpretation of the parasite is 

 promptly disposed of and the latter stated to 

 be a stage in the life history of the common 

 coccidium of fowls and other domesticated 

 and wild birds. This coccidium has been 

 known since Rivolta first described it in 1878. 

 Though I felt grave misgivings concerning 

 the position taken by these writers, I neverthe- 

 less refrained from expressing my views until 

 a full report should have appeared. In the 

 meantime my patience has been tried by re- 

 peated iterations of the statements in various 

 journals, scientific and practical, without any 

 offer of proof that their position had any 

 ' 1908, N. S., Vol. XXVII., p. 994. 



basis in fact. At last two and a half years 

 after their preliminary statement a bulletin' 

 appears. 



As an illustration of the way " facts " will 

 grow when unchallenged I select the following 

 statements from preliminary papers: 



Since the investigations of Theobald Smith 

 published in 1S95 it has been commonly believed 

 that the disease [blackhead] is due to an amoeba, 

 A. meleagridis Smith. The present writers 6e- 

 liev^ they have demonstrated, however, that the 

 disease is caused by a coccidium which according 

 to the nomenclature adopted may be a variety of 

 C. cuniculi and that 4. meleagridis is probably 

 the schizont stage in the development of the coc- 

 cidium.* 



The discovery that the so-called blackhead of 

 turkeys so common in this country is a form of 

 coceidiosis (Science, 1908, N. S., XXVII., p. 994) 

 and that the causative organism C. cunic-uli is one 

 of the most important factors in the causation of 

 the so-called white diarrhoea of chicks and of some 

 cases of roup in fowls, has called the attention of 

 the student of protozoology in this country to the 

 presence of a protozoan parasite whose ravages 

 are annually costing the country hundreds of 

 thousands of dollars.^ 



These excerpts speak for themselves. A 

 " belief " becomes a " discovery " a year later, 

 although no published data accompany the 

 belief or precede the discovery. The discovery 

 consists in fitting together two parasites both 

 regarded as distinct for many years. Fur- 

 thermore, the avian coccidium is identified 

 with the rabbit coccidium without proof. It is 

 made the " most important factor " of a diar- 

 rhceal disease of chicks and of roup in fowls, 

 also without proof. Eoup has defied many 

 investigators and is due probably to an in- 

 visible virus. 



The full report now before us confirms my 

 suspicions that the demonstration and discov- 

 ery represented merely an inference or hypoth- 

 esis. Yet upon this the report is built as if 

 it were an assured fact. Nothing whatever 



'No. 141, Rhode Island Agric. Exp. Station. 



' Italics mine. 



' Cole and Hadley, Science, 1908, N. S., XXVII., 

 p. 994. 



"Hadley in Centralbl. f. Bakt., Erste Abth. 

 Orig., 1909, 52, p. 147. 



