THE HAEMOFLAGELLATES 



237 



and fertilisation do not take place until the sexual forms are trans- 

 ferred to the gnat. The process in its main outlines has been 

 previously described by MacCallum in another species of HalteridiumJ- 

 Schaudinn adds that, as soon as the parasites leave the warm- 

 blooded host, the megagametocytes become rounded off, rupture the 

 delicate envelope still surrounding them, and then undergo a series 

 of reduction-divisions, after which they are ready to be fertilised. 

 The zygote develops into one of the three kinds of ookinete with 

 which this description began. 



Leucocytozoon (" Trypanosoma ") ziemanni. Even more surprising 

 are the data put forward by Schaudinn in the case of the other para- 

 site (or set of parasites) upon which he worked. Just as a species 

 of Halteridium is regarded as ontogenetically related to Trypanomorplm 

 noctuae, so Leucocytozoon ziemanni, a parasite of the white corpuscles 

 and erythroblasts, is said to be intimately connected with what has 

 been hitherto taken for a species of the genus Spirodiaeta, a well- 

 known bacterial type. Far from being, however, a true member of 

 the Bacteria, this species at any rate was regarded by Schaudinn 

 as possessing all the fundamental 

 characteristics of a Trypanosome 

 (see Fig. 7, H). 



The plan of the life-cycle is 

 fundamentally similar to that 

 just summarised, the same sets 

 of forms being described. Two 

 or three distinguishing features 

 may be noticed. The indifferent 

 Trypanosomes are extremely 

 spirochaetiform (Fig. 26, A-D) ; 

 after longitudinal fission, the 

 two daughter-individuals remain 

 attached end-to-end (B and c), 

 the resemblance to a Spirochaete 

 being thereby accentuated. 2 The 

 resting-phases, little pear-shaped 



f-\vr 



two 



TIG. 26. 

 A-D, formation and fission of s 



aeti- 



(E and F), are Very Piroplasma- ziemanni \ E, F, resting-phases of same; G, 

 ,\, ' , * ,, , agglomerated cluster of very minute forms. 



like and strongly recall the (After Schaudinn.) 

 Leishman-Donovan bodies. On 



the other hand, the gametocytes (in the blood of the owl) are 

 very large and broad, and distinctly trypaniform, even possessing 



1 See the account of the Sporozon, by Minchin, in this treatise (Vol. I. Part II. ). 



- According to Novy, M'Neal and Torrey (64), Topfer has recently cultivated a 

 true Spirochaete (i.e. a Bacterium) from the owl, which possesses also minute resting- 

 forms. Hence Schaudimi's 'spirochaetiform " Trypanosoma " may have been really 

 this same fyirochaeta. 



