
1905. | | Life History of Trypanosoma balbianii. 3795 
considerable, in many cases encyst at the periphery of the style. In the style 
also many individuals undergo degeneration, the empty shells of periplast and 
torn off undulating membrane occurring at times in considerable quantities. 
When the style disappears production of the gametes occurs, followed by con- 
jugation. When for any reason the oyster is subjected to a hunger period and 
the style disappears, the indifferent forms either encyst or multiply rapidly, 
becoming much attenuated in the process. The female forms are, however, 
more resistent, and under these conditions do not multiply, but after a time 
encyst. Intra-epithelial stages in the gut do not appear to occur. 
Transmission of the parasite appears to take place by cysts alone. 
The points of greatest interest brought to light in the study of Trypanosoma 
bulbianw are perhaps the following :— 
(1) The primitiveness of the nuclear relations in the normal individual. 
(2) The extraordinary variability of the undulating membrane, a 
variability which has not been correlated with any definite conditions of life. 
(3) The method of nuclear change, involving the condensation of the 
spiral nuclear band into a rod which segments into chromosomes. 
(4) The method of encystment and condition of the nucleus recalls the 
bacteria. 
(5) The existence of appearances in the encystment of the female forms 
suggestive of parthenogenesis. 
(6) The method of the formation of the male gametes, involving a longitu- 
dinal division and the extrusion of nuclear substance. 
(7) The resistant nature of the female forms and great susceptibility of 
the male gametes to unfavourable conditions. 
(8) The correlation of the production of gametes and occurrence of conjuga- 
tion with the disappearance of the style. 
