
1905.| | Infe History of Trypanosoma balbianii. 369 
the guidance of Dr. von Prowazek, my great indebtedness to whom I here 
take the opportunity of expressing. 
Structure—Exclusive of the male and female gametes, Trypanosoma 
balbianit occurs in two modifications, which will be referred to as the indifferent 
and female forms. | ‘ 
The Indifferent Form (fig. 1).—This is so named as it exhibits no sexual 
characters, and appears to give origin, directly or indirectly, to all the other 
three forms—to the male gamete and female form directly, and to the female 
gamete indirectly through the agency of the female form. 
In outward appearance the indifferent form is an elongated snake-like 
structure varying from about 26 w to 100 wu in length, and from about 0°5 « to 
3 w in breadth.: The diameter is practically uniform throughout, the two 
extremities being rounded off. The body of the cell consists of a homogeneous 
non-granular mass of protoplasm enclosed within a tough pellicule, the 
periplast, which consists of a number of longitudinally-arranged fibrille 
embedded in a structureless matrix. These fibrille are probably the active 


Se) 

4 

Fie. 1.—Diagrammatic representation of indifferent form. n., nucleus in the form of a 
homogeneous spirally-wound band. u.m., undulating membrane. e., thickened 
edge of und. mem. p., periplast. c., chromatin thread connecting nuclear 
band and thickened edge of membrane. 
agents in producing the vigorous and multiform contractions by which the 
animal propels itself through the fluid medium in which it lives. A nucleus 
is present, typically in the form of a spirally-wound band, which extends 
practically from one end of the animal to the other, only a small portion of 
the creature, from 2 to 34 in length at each extremity, being free from it. 
In the resting state the nuclear band is apparently homogeneous, but during 
longitudinal division it can be seen to become differentiated into a spirally- 
wound feebly-staining thread with masses of chromatin arranged along the 
sides at regular intervals (fig. 2,2). The central thread is probably homo- 
logous with the karyosom of other Trypanosomes, while the chromatin masses 
correspond to the rest of the main nucleus. As will, be seen later, this central 
thread becomes again differentiated from the rest of the nucleus during the 
encystment of the female forms. The nuclear band is thus probably to be 
