334 PROFESSOR W. C. WILLIAMSON ON VOLVOX GLOBATOR. 



defined and compact form of the organs lodged in these cavi- 

 ties, is also another peculiarity of animals. In plants, the 

 organs for special purposes are not embodied in one mass, 

 but are distributed over various parts of the individual." 

 That all this is strictly true, when merely applied to the 

 higher forms of each kingdom, cannot be denied. But 

 surely the vegetable nature of the sponges and Amcebce, 

 closely allied as these groups are to the Foraminifera and 

 jther Protozoa, cannot be regarded as so indisputably set- 

 tled as to admit of the recognition of the above generaliza- 

 tion. If the latter objects are animals, they present all the 

 features just quoted which these distinguished writers con- 

 sider characteristic of animal life. It is only proper to add, 

 that they entertain no doubt of the vegetable nature of 

 sponges. They also consider " voluntary motion and sen- 

 sation" as characteristic of animal life. The existence of 

 the latter function would be difficult to prove in many un- 

 doubted animals ; and on comparing the motions of the 

 Volvox, of many Confervoid spores, and other vegetable 

 organisms, with those of the ciliated germs of numerous 

 Acrite animals, as well as those of the infusorial Animalcules, 

 we at once perceive that the one class exhibits just as many 

 evidences of volition as the other. 



In such examples as that now under consideration, it 

 appears to me, that we cannot safely do morie than ascer- 

 tain to which of the two kingdoms the object presents the 

 greatest amount of affinity on the one hand, and the fewest 

 discrepancies on the other. By thus weighing the various 

 positive and negative arguments, we may arrive at an accu- 

 rate conclusion, without the necessity of attempting to 

 succeed where so many able men have previously failed. 

 On subjecting the Volvoon to what is apparently the only 

 kind of test that the present state of knowledge renders 

 practical, we are brought to the conclusion, that its true 

 place is amongst the vegetable Algae, rather than amongst 

 the animal polygastric Infusoria. 



