326 PROFESSOR W. C. WILLIAMSON ON VOLVOX GLOBATOR. 



Implanted above each of the green areas, we have two 

 cilise, or " proboscides" of other writers {Fig. 5 e, and 12 c), 

 to which further reference will be made. 



On rupturing a Volvox between two glasses moistened 

 with water, we find ample confirmation of the accuracy of 

 the above views. By the bursting of the organism, a num- 

 ber of cells along the torn margins are laid open. The 

 cell-contents of the cells whose outer walls are so ruptured, 

 instantly lose their stellate form and become spherical {Fig. 

 4 d and 12) ; a result produced by the liberation of the 

 elongated processes from their points of attachment to the 

 cell-walls, and which is probably owing to the existence 

 of some elasticity in the inner cell-membrane. 



But whilst many of the cell-contents, thus altered in their 

 contour, escape from the cavities of their respective outer 

 cells, individuals are sometimes retained in connection, by 

 means of a long thread, as at Fig. 4 d and e. It is evident 

 that the whole of the cell-contents, with the exception of 

 the brilliant spherical granules, are remarkably ductile and 

 cohesive. They may be drawn out into long threads to the 

 extent of several times their own diameter {Fig. 4 e). 

 This singular viscid character readily accounts for the ex- 

 tension of the stellate processes, on the enlargement of the 

 areas of the individual cells. It is evidently the property 

 which has caused the elongation of the threads at the 

 expense of the central mass, and is possibly owing to the 

 existence of a large quantity of gummy matter in their sub- 

 stance. In a little time after water has obtained access to 

 the interior of the Volvox, we find that an analogous change 

 gradually steals over the contents of all the other cells. 

 The processes become successively detached from the cell- 

 wall, and are drawn in towards their respective centres, 

 which also become globular {Fig. 12). For a time the 

 cell-contents, though thus altered in form, do not escape 

 from the cells in which they are contained, — as we found 



