1912.] Life-History of Trypanosoma gambiense, etc. 69 



in the gut. The trypanosomes may overflow into the sucking-stomach or 

 crop, but are not permanently established there. The flagellates are, moreover, 

 unable to retain their position in the proventriculus if the fly is subjected 

 to a fast of a considerable duration, such as any period exceeding two or 

 three days. 



Magnification 2500. 



Multiple Forms. — Up to about the 10th or 15th day of the cycle multiple 

 forms such as those shown in fig. 14 may be seen in certain cases. The 

 evidence is largely in favour of these being degenerative stages but is not 

 sufficient to entirely exclude the possibility that some of them (compare fig. 15) 

 may not be involution-forms or resting phases capable of further development 



