ZOOLOGY: R. ERDMANN 
507 
somes is not yet assumed and the nucleus is not yet distinguishable. 
There remains, therefore, an interval of 36 hours after the new inocu- 
lation of strain M in which no typical trypanosomes could be discovered 
in the peripheral circulation. Crawley^"^ shows that long continued 
Fig. 4 Fig. 5 
use of dark-field illumination is inimical to protoplasm. Consequently 
great care must be taken in interpreting the different elements of the 
blood. The use of plasma instead of blood obviously eliminates many 
difficulties, because only a few elements of the blood are transferred 
into this culture medium. 
