218 Uiiiversitfi of Califoniia Publications in Zoohigij [Vol.16 



A comparison of this figure with that of Schizotrypanuin cruzi 

 (fig. 7) reveals an essentially similar structure, barring only the extra 

 chromatin granules in Prowazekia lacertae. This denotes a relation- 

 ship between these two bodies as intimate as that ascribed to the same 

 organelles in the trypanosomes. 



Similar structures have been figured for Trypanosoma noctuae by 

 Rosenbusch (1909, pi. 25, fig. 10), for T. rotatorium by Machado (1911, 

 pi. 7, fig. 3; pi. 8, fig. 50), in T. lewisi by Carini (Mayer, 1911. pi. 6, 

 fig. 8), and in Crithidia leptocoridis by McCulloch (1915). This does 

 not appear in all the figures given by these investigators, but much of 

 the work has been done with Giemsa preparations and this is a difficult 

 point to establish by that method. 



Neither is its occurrence constant in Prowazekia lacertae. Various 

 modifications of this suspensory apparatus may be frequently met 

 with (figs. 26, 28, 30), or even forms in which it seems to have totally 

 disappeared (fig. 29). The parabasal body itself is also modified in 

 several ways. Figure 27 shows a well-developed fibrillar connection 

 with the parabasal body which is here elongated into a long, band- 

 like structure looped up around the nucleus. This band-like form is 

 of frequent occurrence (figs. 28-30) and may assume various posi- 

 tions, sometimes occupying the whole central part of the cell. The 

 amount of the chromidia in this organelle also varies greatly in 

 different individiials, the entire structure sometimes appearing as a 

 densely staining mass (fig. 31), and again showing more or less of a 

 definite organization with very little chromidia. 



The compact form shown in figures 31 and 32 is not far remx)ved 

 from that of Prowazekia cruzi (fig. 20), differing from it mainly in 

 that its position is posterior to the nucleus, and farther removed from 

 the blepharoplast. Division in the two species is essentially the same, 

 consisting of an elongation usually in a tranverse direction in the cell 

 and a simple constriction in the middle (figs. 32, 33). 



The connection of this body with the blepharoplast and the tlif- 

 ferent stages shown of its backward migration and change into an 

 elongated, band-like form, afford very strong evidence for the view 

 that we are here dealing with the same structure found in Prowazekia 

 cruzi and in the trypanosomes, namely the parabasal body. 



It is : ( 1 ) a body originating from the blepharoplast and intimately 

 connected with it as, presumably, an accessory kinetic structure ; 

 (2) the steps in its backward migration may be followed, showing that 

 this process is comparable with the backward migration of the para- 



