PRESIDENT S ADDRESS. \XV 



the fact of its solid consistency. Tliis is nmcli more easily 

 observed if the Volvoces are aj^ain strained oti" and placed in a 

 compressor with a little clean water. 



With this elucidation it is no lonij^er difficult to understand 

 how. as the young Volvoces continue their growth within the 

 parent, there comes a time when the overstrained envelope 

 bursts, and, as before remarked, they escape with so much 

 energy. The manner and means of escape of the young 

 is often seen in a gathering of mature specimens, especially if 

 the weather is fine and warm, but this result may be brought 

 about much sooner by the addition of a little carbolic acid, 

 which will often cause nearly every one to burst within a very 

 short space of time, a fact I have noted to my chagrin when 

 mounting slides of this beautiful organism. 



Solid is too strong a word, perhaps, to apply to matter 

 which cannot be more than gelatinous, and is here used only in 

 antagonism to the word hollnu- : but, if the spheres be stripped 

 of their outer green covering, this envelope collapses, while the 

 contents retain their spherical form, as is readily seen by the 

 displacement of the carmine. 



(Added April Srd, 1888. j 



Since I read this note, which necessarily caused much 

 discussion at the time, it has been confirmed by several 

 observers, and, as it has not been published, is introduced 

 here. 



I have tried the further experiment of freezing a mass of 

 Volvox upon a slide, and with a sharp knife cutting some 

 sections, which were found to retain the matter within the 

 green envelope, and this internal matter, whatever it may be, 

 proved to be sufficiently dense to support particles of carmine, 

 dirt, or any other solid matter which lodged upon it. 



The contents are so perfectly colourless that they are quite 

 imperceptible in water, unless it be charged w^ith suspended 

 matter, and then only show their presence by displacing this 

 matter from the space which they occupy themselves. 



