172 H. M. WOODCOCK. 



with haematoblasts, which then fail to become red blood- 

 corpuscles. In the former genus young, non-sexual or 

 *' indifferent " individuals attach themselves firmly to the er}'- 

 throcytes by the flagellar end and come to lie parallel to the 

 surface of the corpuscle. They then enter on a resting period 

 and sink slightly or nestle into the latter, incurving its sui'face 

 but nevertheless remaining ectoglobular.^ The only part of 

 the substance of the corpuscle used up by the parasite is that 

 represented by the space which it has hollowed out, and upon 

 which it pressed. After growing for a certain time the pai*a- 

 site leaves the erythrocyte without having decolourised or 

 apparently injured it to any serious extent. Female forms, 

 on the other hand^ penetrate into the corpuscle and become 

 endoglobular/ growing at the host-cell's expense^ and eventu- 

 ally absorbing all its haemoglobin, forming therefrom the 

 well-known pigment, just like the human malarial parasites. 

 A slightly different course is followed by Trypanosoma 

 ziemanni with respect to the white corpuscles. In the first 

 place the parasites become attached by the non-flagellate end, 

 and secondly, the sexual forms of this Trypanosome are so 

 large that it becomes, here, rather a question of the parasite 

 taking up the leucocyte than the reverse.^ Fig. 33 b shows a 

 fully-grown female form just attached to a uninuclear leuco- 

 cyte. According to Schaudinn, the parasite (which proceeds to 

 enter upon a resting-phase as soon as attachment is effected) 

 draws up, as it were, into itself the leucocyte, so that this 



' Schaudinn finds an exactly parallel behaviour in the case of the indiffe- 

 rent ("schizont") and female forms of the tertian parasite; hence there is 

 equal truth both in his and in Argutinsky's views with regard to this point. 

 See also Minchin (1. c, p. 240). 



' Both Danilewsky (1. c.) and Ziemann (121) agree with Schaudinn in 

 attributing to this parasite a leucocytic habitat (whence its original name 

 of " Leucocytozoon "), and the latter author, moreover, is inclined to admit 

 the possibility, at any rate, of the leucocytes being enveloped by tlie para- 

 sites. Laveran (37) on the contrary, in his recent description of this form 

 in the " Hsem amoeba "-phase, regards the parasites as invading hsematids 

 (red blood-corpuscles) which become greatly altered and fusiform owing to 

 their presence. 



