HyEMATOZOA OF VERTEBRATES. 
87 
These trophozoites present slight differences from those of 
H. nicorice . Their size is rather larger, 12 microns (*012 mm.) 
in length, the protoplasm stains a uniform blue leaving no clear 
pole, the reddish-blue stained nucleus is denser and is placed 
near the anterior pole. The greater density of the nucleus is 
evidenced not only by the closer aggregation of its chromatin 
material, but also by a greater resistance to the staining reagent. 
In many instances the nucleus of the parasite is hardly or not 
stained at all. If the parasite has been artificially set free on the 
slide, its nucleus is certain to be well stained. 
It should perhaps be noted that the host-snake had died some 
hours before the examination of its blood, but this fact had 
nothing to do with the presence of the trophozoites. 
The latter when kept fresh under observation in a hanging 
drop for several days undergo no apparent change until they 
disintegrate. 
2.—Free Infection. 
We do not know the fate of the U-shaped trophozoites 
described above, nor do we know how long they remain in a 
particular phase of growth within the corpuscle. Just as they 
remain unchanged for days in a hanging drop, so they may live 
for months without undergoing much appreciable change within 
the blood-cells of the host. 
At last there comes a crisis in the life of the parasite when 
something must happen to perpetuate its existence. There are 
several critical stages in the life cycle of other Haemosporidia and 
the same fact probably holds true for the Haemogregarines, only 
here the stages have not been properly defined. A form of 
reproduction by multiple fission resulting in the formation of 
eight daughter trophozoites or merozoites has been described by 
Laveran* (cf. fig. 22, H. nicoriae). 
A few days after the endoglobular parasites had been found in 
the young Tropidonotus a very large freshly killed snake of the 
same species came into our hands.f A hasty examination of a 
drop of blood revealed the presence of extraordinary numbers of 
free, actively moving haemogregarines in the blood-plasma. 
Numerically this invasion would compare favourably with a rich 
infiltration of Trypanosoma, a comparison which is all the more 
appropriate on account of the activity of movement and the 
disturbance created among the corpuscles. The analogy is still 
further strengthened by the behaviour of these highly motile 
* Cf. Minchin, E.A., op. cit., p. 266, fig. 77 j. 
f Its length was 3 feet 8 inches, and its girth more than twice that of the 
younger specimen. 
