94 J. B. CLELAND AND T. H. JOHNSTON. 



seemed distinctly traceable, as it took spiral windings round 

 a delicate blue protoplasmic envelope. In some cases, the 

 anterior quarter of the deeper stained axial filament was 

 thicker than the remaining three-fourths, and this part 

 perhaps represented the 'middle' piece of the spermatozoon. 

 Sometimes a delicate blue protoplasmic envelope could be 

 seen surrounding this part ; for the middle two-fourths, 

 however, this envelope was often very noticeable and was 

 always at one side, the concave, of the axial filament, as 

 though this wound round the outside of it, much as the 

 flagellum of a trypanosome does the body of that organism. 

 Usually this protoplasmic envelope ceased to be evident 

 for the last fourth of the flagellum, but several instances 

 were seen in which either the axial filament ended in 

 extreme tenuity some considerable distance from the end, 

 which appeared as a delicate faint blue spiral, or had been 

 torn from this protoplasmic bed and projected as a naked 

 end while its normal situation was indicated by a similar 

 delicate spiral. The nucleus could not be definitely dis- 

 cerned. 



2. The broad, truncated, band-like forms — These showed 

 a similar pointed, delicate, blue end, which was succeeded 

 by a rather broad band-like reddish structure, narrowing 

 somewhat posteriorly but not ending in a definite axial 

 filament. A centrosome was sometimes discernible near 

 the junction of the pointed end and deep stained portions. 

 No definite nucleus was visible, and no definite protoplasmic 

 envelope. Numerous forms were seen intermediate between 

 these two types. 



Sections of the testes, embedded in paraffin and stained 

 by iron-haematoxylin and eosin, showed vast numbers of 

 the spermatozoa in situ, grouped in masses. The spiral 

 windings were conspicuous and all parallel. Nearly all 

 were of the thin type but scattered, broader ones could 



