XOTES ON SPOROZOA II. 
189 
reasons, which, iP not jnst the same, are of a similar order. 
Thus the avian blood-parasite known as Lencocy tozoon 
is distiiiefuished from that known as Halteridinm, althoirn'li 
there is little doubt that the two types are very similar in 
structure and in regard to the essential features of the life- 
history; the principle difference is that of habitat, the one 
form (Ealter id i u m) being parasitic in the red corpuscles, 
the other (Leucocy tozoon) in the uninuclear leucocytes.^ 
Nevertheless, it is very useful to continue to distinguish the 
two types as separate genera. And similarly as regards 
these reptilian blood-parasites, as a means of indicating at 
once the characteristic difference in the effects on the host- 
cell, it is most convenient to retain the generic names Kary o- 
lysus and Haemogregarina for the karyolysing and non- 
karyol}’sing group of species re.spectively. 
Of late years several workers have given accounts of 
Ilasmogregarines from lizards, for the most part recording 
the occurrence of new pai'asites — or at any rate, parasites 
regarded as new — in various additional hosts; several of these 
ai-e undoubtedly Karyoly su s-forms. The parasites of the 
different species of Lacerta have been studied chiefly by 
Laveran and Pettit and by Franca. In their first paper, 
Laveran and Pettit (14) describe the parasites they observed 
in L. muralisand viridis, more frequently in the former 
species. They distinguish three different type.s, all of which 
they consider to represent Danilewsky's parasite, which they 
term II. lacerta); the authors thus use the correct specific 
name, but prefer to keep the parasite in the genus Hasmo- 
gregarina. The first two types are the same as those which 
I have again found, that is to say, young scliizonts and older 
ones. The only point which requires notice is that the authors 
consider there is no capsule, but merely a shrinkage space 
around the second type of form ; this is certainly a mistaken 
view on their part. Tlie third form of parasite is, in nij' 
' The different liabitat ex-plains, of course, the fact that tlie one para- 
site (Halteridinm) produces melanin pigment, while the other 
Leucocy tozoon) does not. 
