XXIV PKESIUENT S AUDKESS. 



Seen in the microscope in tlie perfect state, in all its living 

 beauty, it most certainly does appear, as usually described, a 

 " hollow pellucid globe," and a solution to the difficult problem 

 as to the possible nature of the force which causes the young 

 Volvoces to escape from the parent envelope with so much 

 energy is by no means apparent. 



As frequently happens, little accidents lead to the discovery 

 of facts which otherwise seem out of one's reach, and a few 

 years ago, when I made frequent collections of this organism, I 

 gathered some containing the rotifer which is said to make 

 Volvox its nest, Notoinmatd panisitd of Ehrenberg, and, while 

 watching these little fellows in the home of their adoption, was 

 surprised to see that they were eating something of sufficiently 

 solid consistency to keep them in position in a part of the Volvox 

 where, according to the hollow-sphere theory, there should be 

 nothing to eat, or to bear their tiny weight. The rotifers usually 

 made their way to the Volvoces within the parent, where they 

 appeared to take up their quarters. The next thing noted 

 was that, when Volvox was placed upon white blotting paper, 

 which of course left them high and dry, they still retained a 

 good deal of their rotundity, and became flattened much less 

 than would be expected if they were reall}' hollow. 



However, a little experiment, which it is easy lor everyone 

 to try, shows that Volvox is without any cavity whatever, and 

 that the perfectly transparent contents of the globe appear to 

 possess little if any less firmness than the pellicle or membrane 

 which forms its periphery. This may be shown by taking Volvox 

 in good quantity and straining the water from them ; by this 

 means a little mass may be obtained. Let the Volvoces thus 

 collected be taken up rather roughly by means of a syringe, 

 and placed in water containing carmine or any fine solid 

 matter. It will probably be found that some of the Volvoces 

 have been broken, some perhaps even into fragments which 

 still display the rolling motion. Now if a little care is used in 

 examining the ruptured specimens it will be seen that the 

 carmine adheres to any surface thus exposed, at once displaying 



