0. Dobell 167 
animals as varieties of the same species. In most works dealing with the 
Coccidia they are called collectively “ Coccidium bigeminum L” 
Having said so much by way of introduction to this section, 1 will now pass 
on to its subject proper. I shall take the various authors in chronological 
order, as far as this is possible. 
It has already been noted that Davaine (I860) saw Gubler's hepatic 
coccidia, and tentatively concluded that thev were similar to those found in 
rabbits ( i.e . to Eimeria stiedae). He called all these parasites “ oviform bodies,” 
and was inclined to regard them as the eggs of worms. 
Of much greater importance historically are the opinions of Leuckart. As 
already noted, he first expressed the opinion that Gubler’s case was “of 
doubtful nature.'' He included with it Virchow’s and Kjellberg’s cases 
(Leuckart, 1863, p. 49, footnote). Later, however, he decided that Gubler’s 
case was one of “ psorosperm " infection, and similar to Dressler’s case and 
others which he had since had communicated to him (Leuckart, 1863; 
Appendix, p. 740). In his later work (Leuckart, 1879) he discusses all the 
parasites in greater detail. Translated into modern terms, his opinions were 
as follows: all the coccidia found in the human liver 2 are of the same species 
as those found in a like situation in the rabbit. In other words, all are Eimeria. 
stiedae (= Coccidium oviforme). All the coccidia found in the intestine of man 3 , 
the rabbit, the cat, and the dog, also belong to one species—namely, Eimeria 
perforans (= Coccidium perforans). This species therefore embraced Jsospora 
bigemina in Leuckart’s estimation. 
Leuckart believed that human beings acquire their infections through con¬ 
tact with infected animals. He thus regarded the rabbit as a source of human 
contagion, for both the hepatic and intestinal coccidia; and for the latter, the 
1 Although the organisms in question are now very generally known as Isospora bigemina Stiles, 
it seems probable that this is not their correct name. If we exclude Rivolta’s lengthy Latin 
appellation (see preceding footnote) as not conforming with the rules of binominal nomenclature, 
the first name given to them seems to be “ Coccidium Rivolta ,” bestowed by Grassi (1879 a). Why 
the specific name is written in the nominative instead of in the genitive case is not clear. At first 
sight it appears to be a lapsus calami; but Grassi repeats the name in the same form in at least 
two later papers (Grassi, 1882, 1883). It is clear, however, that he regarded the name as binominal, 
and intended it as a mark of honour to Rivolta. My own view is that this name should be amended 
by substituting the correct generic name, and putting “ Rivolta ” in the genitive case. The correct 
name would then be Isospora rivoltae Grassi (1879), which has priority over 1. bigemina Stiles 
(1891). If anybody should object to this specific name on the grounds of Art. 14 of the International 
Rules, I would remark that the genitive termination -ae is good Latin for the name of a man 
ending in -a ( e.g . Caligula, -ae; Cotta, -ae, etc.) in spite of the Rules; and further, that if Eimeria 
stiedae is an acceptable form of commemorating the Russian naturalist, then Isospora rivoltae should 
be equally acceptable for the Italian. Forms such as “ rivoltai" appear to me to be unnecessary 
and objectionable solecisms. The difficulties connected with the generic name Isospora will be 
considered later. To avoid confusion, I shall, however, continue to call the coccidia of the cat and 
dog Isospora bigemina in the present paper. 
2 Leuckart (1879) knew of four cases—Gubler’s, Dressler’s, and the two cases sent by Peris 
(from Sattler and the von Sommerring collection). 
3 The only human cases known to Leuckart were those of Kjellberg and Eimer. 
