318 
Haemogregarines 
is, on the contrary, in nearly all cases hypertrophied and elongated parallel 
to the long axis of the parasite (cf. Fig. 4, and Figs. 5, 6, 7), whilst the interior 
structure of the nucleus loses its normal aspect. The regular rounded lumps 
of chromatin are no longer visible, and the chromatin mass appears to be 
entangled in irregular accumulations and strands. In some places vacuoles 
are visible (Fig. 5). In a word, indications of karyolysis are present. 
Possibly in this case the diminution in the size of the erythrocyte presents 
already a secondary stage in the degeneration of the corpuscle, as this process 
usually begins with a hypertrophy of the cell and nucleus, succeeded by a 
diminution and shrinkage of the cell and fragmentation of its nucleus. 
The haemogregarine described is disposed parallel to the long axis of the 
host cell, sometimes closely adjacent to the nucleus of the latter (Fig. 5). The 
body of the parasite is elongated, slender, never bent over on itself, only the 
ends may sometimes be slightly bent inwards (Fig. 5). Measurements: 
length 15 to 16/x, breadth 2-25/x; size of normal erythrocyte 15-5/x x 11/x. 
The protoplasm stained very feebly in my preparations; nevertheless, it is 
possible to trace a slight granulation in it. The nucleus is elongated (3/x long), 
more or less centrally located. 
In general appearance, form of the nucleus, and action on the host cell, 
our parasite resembles Haemogregarina (Karyolysus) crotali from Crotalus 
confluentus (Sambon, 1909), but it still more closely resembles one of the 
stages of Karyolysus gracilis described by Wenyon (1908) from a lizard— 
Mabuia quinquetaeniata. Like ours, this form presents the only stage found 
in the peripheral blood, whereas all the other stages of the asexual cycle take 
place in the internal organs (liver cells). Wenyon, and subsequently Reichenow 
(1912), regarded this form as a gametocyte (as yet sexually undifferentiated). 
Taking into account the pathological action of our parasite on the blood 
corpuscle infected by it, and its likeness to the representative of the genus 
Karyolysus mentioned above, it is possible to refer our form to the same genus. 
Although at present we are provided with a description of the complete life- 
cycle of one representative of this genus —Karyolysus lacertarum (Reichenow, 
1912), which affords us an exact criterion for distinguishing between the genera 
Haemogregarina and Karyolysus independently of their pathological role—the 
old classification also remains in force for parasites in which the complete 
life history has not yet been studied. According to this classification, to the 
genus Haemogregarina are referred all forms which do not do any injury 
to the nucleus of the host cell, whereas all those that produce such an effect 
are referred to the genus Karyolysus (Reichenow, 1912; Doflein, 1916). Not¬ 
withstanding the close resemblance between our form and K. gracilis , I prefer 
to leave the question regarding the species of our parasite open, on account 
of the presence of only one stage in my preparations. 
