C. Dobell 1.55 
that all were cases of hepatic infection—Leuckart himself having never studied 
or described any cases of intestinal coccidiosis in man. 
Rivolta's cases. It is generally supposed that cases of human coccidiosis 
were studied and described by Rivolta, and his name is almost invariably 
cited as one of the authorities on the subject. The facts, however, appear to 
be as follows. 
Rivolta (1873) mentions somewhat casually (p. 565) that he found some 
‘‘corpuscles in the faeces’’ of “a man afflicted with intermittent feverand 
he gives (Plate X, fig. 317) some rude sketches of them, described (on p. 580) 
as “corpuscles in the faeces of a man suffering from tertian fever." The bodies 
in question were “large white cells, with somewhat indistinct contour and 
homogeneous whitish contents; they had an oval shape, some of them also 
being round or piriform ” (p. 565). To judge from the figures, they were about 
8/jl in diameter: and although it is impossible to identify them. I may hazard 
the guess that they were the cysts of Entamoeba nana, which are far from un¬ 
common in human faeces. Rivolta himself does not even suggest that his 
“corpuscles” were coccidia. So far as I can discover, he nowhere refers to 
them again; and in none other of his publications is there any mention of his 
having found coccidia—or any other protozoa—in the faeces or tissues of man. 
Grassi (1879), however, cites the above passage from Rivolta, and compares 
his findings with the supposed “ Psorosperms ” which he himself found in the 
faeces of human beings. But as we shall see (vide infra), Grassi 5 s own “coccidia" 
were not coccidia at all, but the cysts of other protozoa. 
In a later work, Rivolta (1878) proposes the name “ Cytospermium hominis ” 
for the “psorosperms” found in man by Eimer (1870). The name is proposed 
explicitly for these forms, and not for any organisms which he had himself 
studied or described. Its application turns, therefore, upon the identification 
of Eimer’s parasites. 
From a careful studv of all the available sources of information, I have no 
longer any doubt that Rivolta neither discovered nor described any coccidia 1 
parasites of man, and that the cases attributed to him are due to a mistake 
which has become traditional. Its origin, I believe, is to be traced to Blanchard, 
who has been copied—without verification, and often with inaccuracy—bv all 
later writers on human coccidiosis. But I shall return to this point later. 
Grassi’s cases. Grassi, like Rivolta, is almost invariably cited as a dis¬ 
coverer of coccidia in man; and, as I shall attempt to prove, with equally little 
justification. 
As noted above, Grassi (1879) described some “corpuscles” which he had 
found in human faeces and which he regarded at the time as coccidia. They 
were found in two cases—a boy and a young man—in one of whom the 
infection was followed for some two-and-a-half months. From the brief 
description and figures in the original paper it is clear that the “corpuscles" 
were not coccidia at all, but probably the cysts of Giardia (= Lamblia) in - 
