SCHIZOTRYPANUM CRUZ I 429 



In the Invertebrate.- — -The further development takes place in the 

 bug Lamus megistus {Triatoma megista) and allied forms, in which 

 Chagas notes two forms of development : the first is considered to be 

 sexual, and the second to be asexual. 



The sexual method is as follows: — In about six hours after the 

 ingestion of blood the kinetonucleus moves close to the tropho- 

 nucleus, with which it possibly blends ; the fiagellum and undulating 



Fig. 115. — Schizotrypanum cvuzi Chagas: Development in Lamus megislus 



{Triatoma megista). 



(After Chagas.) 



1-6, Forms found in the mid-gut of Lamus megistus; 7, flagellate forms 

 found in the posterior gut of L. megistus. 



membrane are now usually lost, but some forms retain the fiagellum. 

 The parasite now becomes rounded, and multiplies rapidly by divi- 

 sion, but after this has ceased it becomes pear-shaped, develops a 

 fiagellum, and becomes a crithidial form, and then passes into the 

 cylindrical portion of the intestine, in which it can be seen in about 

 twenty-five hours after the ingestion of blood. These crithidial 

 forms can also be found in the rectum and in the faeces. The final 



Fig. 1x6. — Schizotrypanum cruzi Chagas. 

 (After Chagas.) 



Forms found in the salivary glands of Lamus megistus {Triatoma megista). 



stage is a small trypaniform type — i.e., long, slim forms, with band- 

 like trophonucleus and large kinetonucleus. These are found in 

 the hind-gut in the body cavity, and in the salivary glands, and 

 are the forms by which the parasite is transmitted to a new verte- 

 brate host. The development in the bug requires at least eight days 

 for its completion. 



The|asexual method is a constant process, and resembles the 

 growth seen in artificial cultures, and is a simple multiplication, 

 giving rise to crithidial forms which are found principally in the 

 hind-gut. 



