1892.] NEW-YORK MICROSCOPICAL SOCIETY. IS 



middle ground, we should find their lines of relationship leading 

 pretty clearly in one or the other direction. At any rate we 

 should learn that what had an animal origin continues as animal 

 and ends as animal ; that what began as vegetable remains vege- 

 table to the last ; — both completing sooner or later a circle of ex- 

 istence limited by a law of inheritance of which we have not as 

 yet found the secret. 



The difficulty with this matter, as well as with the subject of 

 vitality, is that we look for single distinguishing signs when we 

 ought to take into consideration a whole series of phenomena at 

 once. Thus life would prove to be not an entity, an essence, or 

 even a principle, but rather a process. In like manner, the crite- 

 rion of animal life, as distinguished from vegetable, would not be 

 found in assimilation, sensation, self-motion, or any other one 

 thing, but in a group of actions and attributes, by their sum-total 

 turning the scale to the animal side. 



In his interesting discussion of this topic, Prof. Huxley reaches 

 the conclusion, now generally accepted, that the nearest ap- 

 proach to a definite dividing line is in the fact that the plant 

 can make the peculiar nitrogenous substance called protein, while 

 the animal must get it from the vegetable realm. " Thus," he 

 says, " the plant is the ideal proUtaire of the living world, the 

 worker who produces ; the animal, the ideal aristocrat, who most- 

 ly occupies himself in consuming." 



But even the distinction here attempted needs to be fortified by 

 other considerations when we come to particular instances, since 

 Darwin has shown that certain of the higher plants eat, as well as 

 manufacture, protein, and the same fact has been demonstrated 

 as to fungi and many other thallophytes. There is, however, no 

 reason to suppose that diatoms are eaters, although the wander- 

 ings of the free forms have every appearance of being directed in 

 search of food. But to the best of our knowledge and belief their 

 quest is for inorganic pabulum, if, indeed, it has direct relation to 

 food at all and is not, after all, merely one of those curious modes 

 of dispersion with which we are familiar amongst spores and 

 seeds. As far as we know, the diatom protoplasm has no pro- 

 clivity for cannibalism, as all animal protoplasms seem to have. 

 Taking this negative quality for what it is worth, and adding it to 

 the general sum of the diatom's other characteristics which com- 



