1887.] 11* [Cla5T)ole. 



know to the contrary an organism is capable ot existing unvaried for any 

 length of time, through generation after generation, without showing the 

 least tendency toward any other form. As well might the mechanician or 

 the astronomer speak of a " tendency to motion " in the heavenly bodies 

 because he sees them all in a state of active movement. For anything that 

 he knows to the contrary all the matter in the Universe may be capable of 

 lying at rest for countless ages. Matter itself has no tendency to motion 

 or to rest. It is absolutely a creature of conditions and of circumstances. 

 80 we have reason to believe that organisms have no tendencj' to variation 

 or to invariance. Changes if they occur, or their absence if they do not, 

 are simply accidents of the environment. The astronomer sees all mat- 

 ter in motion and comes almost instinctively to the belief that the two are 

 inseparable. The biologist sees every organism varying and grows un- 

 consciously into the opinion that variation Is a necessary concomitant of 

 life. Both are equally unphilosophical. Absolute rest may be almost in- 

 conceivable to the physicist and absolute invariance to the naturalist. 

 Yet both so far as we can know, are thinkable and possible, and both may 

 form a part of the actual scheme of Nature. We see no ground for the 

 expression "tendency to variation." 



iir. 



Vakiatiox not Always Beneficial. 



In the consideration of this part of the subject it will be manifestly 

 impossible within due limits to even notice any large portion of the 

 facts that bear more or less directly on the question. No attempt 

 will therefore be made to take a wide range. Nor is this necessary for the 

 argument. If sufficient proofs can be adduced to show that in some cases 

 the actual variation is prejudicial to the variant the purpose will be 

 served. Yea, more, in logical strictness if a single such case can be 

 established the advocacy of definite variation in a uniformly beneficial 

 direction becomes futile. For unless such beneficial variation be abso- 

 lutely constant and unfailing no object can be attained by maintaining its 

 occurrence in any single instance. 



I propose therefore to limit myself to the presentation of a few of the 

 more conspicuous instances of prejudicial variation, of which some one or 

 more must during a lifetime fall within the cognizance of all who take 

 any interest in the study of Nature. 



I may here remark in passing that of the two authors quoted at the out- 

 set. Prof. Gray does not give a single instance in support of the proposi- 

 tion which he is maintaining and that the only one under discussion by Dr. 

 Carpenter is drawn from the lowest class and one of the most obscure in 

 the animal kingdom — the Rhizopods — among the Protozoa. 



1. Variation in color. — Among the many variations in color constantly 

 occurring among animals is the production of a white descendant from 

 colored ancestors. 



