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Chapter XXV 
Genus Haemogregarina 
The haemogregarines are unpigmented parasites 
mostly found in the blood of cold-blooded vertebrates, 
but also in that of a few mammals. They are endo- 
globular parasites; but with a free vermicule stage. 
The great majority attack the red blood corpuscles; 
but certain of the mammalian forms attack the 
leucocytes. They are, so far as is known, non-patho- 
genic, and they cannot be transmitted by inoculation 
from one animal to another. Schizogony not in¬ 
frequently takes place in the cells of some viscus, liver, 
kidney, bone marrow, etc. The sexual cycle of 
development has only been described in a few cases 
and cannot yet be said to be definitely known. 
According to some authors three kinds of haemo¬ 
gregarines exist in the blood, thus Prowazek, in H. 
platydactyli , describes :— 
Indifferent Forms.- —The nucleus is rich in chroma¬ 
tin and stains very deeply. The protoplasm is dense and 
filled with red staining matter (Romanowsky). These 
forms frequently leave one red cell and enter another. 
Female Forms.- —Broader than the former, and 
frequently found expressed from the cell. 
Male Forms. —Slender, with a chromatin rich 
nucleus, the protoplasm staining a light blue. They 
often contain a blepharoplast. The males are often 
vacuolated. The red cells are often bent by the 
movements of the parasite, and in stained films are 
boomerang or banana shaped. 
Fechnique. —Examine the blood of warm and 
cold-blooded animals. For schizogony make sections 
