C. Dobell 
1o9 
showed “similar caseous foci."' In the ileum were “six papule-like elevations 
with circumferential inflammatory zone,” and in the large intestine “deeply 
congested patches of mucous membrane from 1 to 3 inches square.” The 
• 
caseous nodules—superficially resembling tuberculous lesions—“consisted 
largely of agglomerations of small, oval, egg-like bodies, with granular con¬ 
tents and well-marked capsule." The bodies were found “in the liver cells 
and in the bile ducts," and Silcock states that they were “identical in every 
respect with the coccidia described" bv Leuckart “in cases of parasiticism 
(sic) in man and rabbits by the Coccidium oviforme .” “On cultivating the 
coccidia... by keeping small affected portions of the organs in water... 
psorosperms were freely developed." He remarks that he has nothing else to 
add to Leuckart’s description of the organisms, and gives no figures. It may 
be noted that Silcock s coccidia were apparently present in the liver and in the 
spleen —a remarkable situation. But although lesions are also mentioned in 
the gut, it is not explicitly stated whether similar parasites were found in them 
or not. 
From Silcock's imperfect account it is now impossible to ascertain what he 
really saw. He seems, most unfortunately, to have thought that Leuckart had 
already fully investigated the hepatic coccidia of man—as was by no means 
the case. It seems clear that Silcock s coccidia resembled Eimeria stiedae , 
since he specifically mentions “ Coccidium oviforme.'' But he gives no indica¬ 
tion of their size, and does not appear to have noticed that the oocysts of the 
human coccidium figured in Leuckart are only about half the size of those from 
the rabbit. Moreover, Silcock himself was—all unawares—actually the first 
to study the development of the spores within the oocyst of the human para¬ 
site 1 ; and it is most regrettable that he makes no mention of their number, 
form, or contents, since it is upon these that the identity of the parasite turns. 
Of the human parasite Leuckart saw nothing but the unsegmented oocysts, or 
drawings of them. His figures of “ Coccidium oviforme " relate exclusively to 
the parasite of the rabbit; and his assumption that the two forms develop in 
the same manner, and are, in fact, the same species, is quite gratuitous. 
Silcock gives no reference to the work of Leuckart which he consulted, and he 
obviously cannot have studied his writings with any care. Had he done so, he 
might have been able to add much to our knowledge: but as it is, we can only 
guess what he really found. 
Giles's cases 2 . In a work dealing with kala-azar and ankylostomiasis in 
Assam, Giles (1890) records the finding of numerous “coccidial" infections 
among the natives. Examination of his figures and descriptions leaves no 
doubt in my mind that his “coccidia were really vegetable cell debris in the 
faeces of his patients. They were often present in “astonishing” numbers. 
1 Or, as he termed it, the development of “psorosperms” in the “coccidia” on “cultivation.' 
2 I have here to thank my friends Dr A. C. Stevenson and Dr G. C. Low—the former for 
directing my attention to Giles’s observations, the latter for obtaining his publication for me. 
Parasitology xi 
11 
