PATHOGENIC PROTOZOA OF THE MASTIGOPHORA 425 



bedded in the protoplasm, in part is attached to the edge of the 

 undulating membrane, and in part is free at the anterior end. 

 A nucleus, usually situated near the center or anterior end, may be 

 demonstrated in stained preparations. It is relatively large and 

 granular in structure. The entire body of the trypanosome is 

 mobile, and the organism may vary its shape to some degree. 

 It swims about with the flagellum in front. 



Multiplication is accomplished by a preliminary division 

 of the blepharoplast, followed by that of the nucleus, and this 

 by a longitudinal splitting of the cell to form two individuals. 

 In cultures the cells may frequently be observed in the form of 

 rosettes or clusters, with the flagellar ends pointing out. These 

 rosettes do not occur in the blood. Transverse division does not 

 occur. No conjugation or fertilization process in trypanosomes 

 has been certainly detected. 



Some investigators have believed that trypanosomes in the 

 animal body may have an ultramicroscopic stage in their develop- 

 ment. Bruce and Batemen, in a series of careful experiments, 

 have shown that this does not occur. 



The existence of a regular cycle of changes in the life of a 

 trypanosome is at present a somewhat mooted question. Some 

 investigators believe that they have established the existence 

 of a relatively complex life cycle. Kleine, Bruce, and others 

 believe that certain species of insects which transfer the disease 

 must be considered true hosts, and that they do not become infec- 

 tive for some days in the case of Tr. gambiense about twenty- 

 after biting an infected individual. Rodenwalt and others have 

 found that certain developmental changes take place in the gut of 

 the insect; others have failed to find them. At present it may be 

 concluded that the occurrence of developmental changes has not 

 been satisfactorily demonstrated, although there is good reason to 

 believe that such may occur. Carimi, Schaudinn, and others have 

 recognized what they believe to be an endoglobular stage in the 

 development of the organism in the body. Battaglio claims to 

 have demonstrated for Tr. brucei, Tr. lewisi, and Tr. vespertilionis, 

 a developmental cycle in the blood, which includes sporulation 

 of micro- and macrogametocytes, with formation of micro- and 

 macrogametes. These conclusions have been combated by others. 



