328 PROFESSOR W. C. WILLIAMSON ON VOL VOX GLOBATOK. 



For a short time after the rupture of the Volvoxy the fila- 

 mentous ciliae continue their active whip-like movements ; 

 but these gradually cease, and soon afterwards the filaments 

 detach themselves from the membrane in great numbers, 

 floating away into the surrounding medium. 



I was long puzzled by the appearances which the liberated 

 filaments assume. Soon after they make their escape from 

 these attachments, they appear to become thickened at 

 one end, and assume the appearance of large spermatozoa 

 {Fig. 7 a). I was for some time in doubt whether this was 

 a real bulbous thickening, or whether, as some specimens 

 seemed to indicate, it was merely the result of a flexure of 

 that portion of the filament, which, when in situ, was 

 implanted in the outer membrane; but I am now satisfied 

 that the latter of these is the true explanation. The base 

 of the filament curls up (Fig. 7 b c), and produces the 

 bulbous appearance in question. I am indebted to my 

 friend, Mr. Dancer, for his assistance in this matter ; and, 

 after a very careful examination of the filaments, he has 

 arrived at the same conclusion. The filament is evidently 

 a distinct appendage, and not a mere protrusion of a part 

 of the cell-contents through the small apertures already 

 referred to. This is shown, both by the readiness with 

 which they drop off, and also by the little change which 

 they subsequently undergo, whether retained in the fluid, 

 or dried upon the glass. 



Thus far I have confined my attention to the changes 

 which have alike modified the great bulk of the individual 

 cells ; but there are other phenomena which only affect a 

 few of them. 



Ehrenberg observed, that some <' animalcules" were 

 selected in each VolvoXt to be the seat of changes of a dif- 

 ferent character, and that, by a continued process of divi- 

 sion and subdivision, every one of these became converted 

 into a young Volvox. 



