1910.| and T. rhodesiense as seen in Rats and Guinea-pigs. 221 
The Metamorphosis of Latent Bodies into Trypanosomes. 
This process was observed in life on several occasions, though the complete 
passage from a rounded body to a fully flagellate moving trypanosome was 
only rarely seen (three times), for it is difficult to imitate precisely the 
natural conditions favourable to such a metamorphosis. However, by taking 
rounded bodies, usually obtained from the spleen of an infected rat, in 
a little physiological salt solution, and adding thereto an equal quantity of 
fresh (normal, uninfected) rat’s blood, some of the rounded bodies were seen 
on a warm stage (25° to 35° C.) to grow, each becoming larger and sending out 
a process (text-fig. 2). This pseudopodium-like process lengthens, and a 
flagellum is formed from an area close to the blepharoplast (kinetonucleus). 
At this stage the parasite forms at its drawn-out anterior end an undulating 
membrane along the edge of which the flagellum les and the organism 
TEXT-FIG. 2 represents‘diagrammatically the metamorphosis of a rounded, latent or non- 
flagellate parasite into a flagellate trypanosome (7. gambiense). The rounded bodies, 
obtained from the spleen of an infected rat, were placed in warm, fresh, uninfected 
rat’s blood and watched under the microscope. The total time taken for the 
metamorphosis was about 1 hour. 
somewhat resembles a Crithidia. This transitory stage may be termed the 
crithidial stage. The organism grows and the blepharoplast passes posterior 
to the nucleus, and the trypaniform stage is assumed. 
The evidence of stained preparations (figs. 32 to 40) fully supports this 
mode of formation of flagellate trypanosomes from non-flagellate latent,bodies. 
