200 University of California Puhlications in Zoology [Vol. 16 



presence of a typical spiudle, while they do support the alternative 

 hypothesis that the process is a simple "amitotic" constriction of the 

 parabasal body. 



The figures of Hartman and Chagas (1910) also "fiir Prowazckia 

 gezeigt, dass der Blepharoplast mitotisch teilt. Seine Kernnatur kann 

 danach nicht mehr in Frage gezogen werden." Two figures only are 

 given to substantiate this emphatic statement, both of which are open 

 to question. In their figures 6, 7, 8, of plate 4, the nuclear division of 

 Cercomonas parva is shown and is described thus : ' ' Sie erscheint 

 scheinbar als eine einfaehe Durchschniiring (sog. Amitose)." On 

 plate 8, figure 64, the division of the parabasal body of Prowazekia 

 cruzi is shown. This differs in no wise from the nuclear division of 

 Cercomonas parva, and yet in this case it is called mitotic division. 

 That figure 64 shows an actual division of the parabasal body might 

 be inferred from the fact that the blepharoplast has already divided. 

 Figure 65 is probably an accidental appearance of the parabasal body, 

 as no other signs of division are apparent in the cell ; neither can it 

 be correlated with any other figure given for Prowazckia by these 

 authors, nor with my own observations. 



The undoubted presence in Leishmania, at one stage of the life- 

 cycle, of a motor apparatus connected with a blepharoplast and para- 

 basal body, indicates its relation to Crithidia and Herpetomonas. Its 

 life-cycle also can be correlated with that of these flagellates, so far, at 

 least, as they are accurately known. Here also, as in the other forms, 

 the same conditions are found with respect to the nuclear nature of 

 the parabasal body. 



Franchini (1912), investigating the Leishmania of the digestive 

 tract of Anopheles maculipennis. showed the presence of both para- 

 basal body and nucleus in all developmental stages figured. There is 

 ut evidence given to indicate its heteropole origin, or that its be- 

 havior during division is anything but a simple constriction. 



In the facts as they have been presented here, there has been no 

 undoubted evidence to support the claim made by the upholders of 

 the binuclear theory that the parabasal body of the haenioflagellates 

 is nuclear in nature, arises by a heteropole division, or any other 

 mitotic division, of the nucleus, and is mitotic in its division. On the 

 contrary, the whole evidence seems to show that it is a constant cell 

 organ, with no facts pointing to its origin and that it divides by a 

 simple constriction. 



