70 
The Genus Leucoeytozoon 
though the life cycle of the latter had not yet been discovered. The 
great difference in the two hosts seemed to warrant the conclusion that 
the life-cycles would be so distinct as to justify their inclusion in 
different genera. Accordingly Miller suggests for the rat-parasite the 
name Hepcitozoon perniciosum. It must be very doubtful whether one 
is at liberty to create a new generic name on a mere probability for it 
must be remembered that the life cycle of the frog haemogregarine is 
not known. But the point I should like to emphasise is this that if the 
leucocytic parasites of mammals are to be separated from the haemo- 
gregarines the generic name will be Hepcitozoon. We have seen that 
the generic name Leucoeytozoon cannot be employed for the mammalian 
parasites as it is the true generic name of a distinct avian parasite. 
Towards the end of her paper Miss Porter says “However as the 
structure and life-history of avian leucocytozoa are still subjects of 
controversy and as the name Leucoeytozoon was first applied to parasites 
of birds, and Liihe seems to restrict the name thereto, the generic name 
Leucocytogregarina might be used for the highly specialised parasites of 
mammalian leucocytes which have a different habitat from the strict 
Haemogregarines of red corpuscles.” Miss Porter has still further 
confused the matter by introducing another name though it must be 
evident to her that if the leucocytic parasites of mammals require a 
distinct generic name the recently suggested name Hepcitozoon of Miller 
will have priority. 
In an earlier paper in which Miss Porter describes a leucocytic 
parasite of the mouse she refers to recently described leucocytozoa and 
mentions one discovered by Sambon in the grouse. It was evident that 
here there was a misapprehension that the Leucoeytozoon of birds was a 
parasite closely allied if not identical with the leucocytic parasites of 
mammals. As far as I can recall the literature this is the first instance 
in which such a mistake has been made. In her recent review Miss 
Porter has still further extended this mistake though the suggestion at 
the end of the review of a new generic name seems to indicate some 
doubt even in Miss Porter’s mind as to the validity of this grouping. 
All recent writers on the bird-parasites employ the true name 
Leucoeytozoon and it is for these bird-parasites that this name must be 
used and not for the leucocytic parasite of mammals. As the complete 
life cycle of the haemogregarines has been followed in only one instance 
there are insufficient data for splitting up the group, so that it is at 
present safer to include in the group Haemogregarina the haemogre¬ 
garines of the cold-blooded animals and the very similar parasites of the 
