27G ON THE STUDY OF BIOLOGY x 



losophcrs, turns out to be substantially correct. 

 More than this, when biologists pursue their in- 

 vestigations into the vegetable world, they find 

 that they can, in the same way, follow out the 

 structure of the plant, from the most gigantic and 

 complicated trees down through a similar series of 

 gradations, until they arrive at specks of animated 

 jelly, which they are puzzled to distinguish from 

 those specks which they reached by the animal 

 road. 



Thus, biologists have arrived at the conclusion 

 that a fundamental uniformity of structure per- 

 vades the animal and vegetable worlds, and that 

 plants and animals differ from one another simply 

 as diverse modifications of the same great general 

 plan. 



Again, they tell us the same story in regard to 

 the study of function. They admit the large and 

 important interval which, at the present time, 

 separates the manifestations of the mental facul- 

 ties observable in the higher forms of mankind, 

 and even in the lower forms, such as we know 

 them, from those exhibited by other animals; but, 

 at the same time, they tell us that the founda- 

 tions, or rudiments, of almost all the faculties of 

 man are to be met with in the lower animals; 

 that there is a unity of mental faculty as well as 

 of bodily structure, and that, here also, the differ- 

 ence is a difference of degree and not of kind. I 

 said " almost all," for a reason. Among the many 



