106 THE CELL DOCTRINE. 



was more or less hidden, in the living corpuscle, and 

 is called its nucleus. Corpuscles of essentially similar 

 structure are to be found in the skin, in the lining 

 of the mouth, and scattered through the whole frame- 

 work of the body. Nay, more, in the earliest condi- 

 tion of the human organism, in that state in which 

 it has just become distinguishable from the egg in 

 which it arises, it is nothing but an aggregation of 

 such corpuscles, and every organ of the body was, 

 once, no more than such an aggregation. Thus a 

 nucleated mass of protoplasm turns out to be what may 

 be termed the structural unit of the human body. As a 

 matter of fact, the body, in its earliest state, is a 

 mere multiple of such units ; and, in its perfect con- 

 dition, it is a multiple of such units, variously modi- 

 fied." The formula which expresses the essential 

 structural character of the highest animal, very 

 nearly covers all the rest, as the statement of its 

 powers and faculties covered that of all others. 

 "Beast and fowl, reptile and fish, mollusk, worm, 

 and polype, are all composed of structural units of 

 the same character, namely, masses of protoplasm 

 with a nucleus. There are sundry very low animals, 

 each of which, structurally, is a mere colorless blood- 

 corpuscle, leading an independent life. But, at the 

 very bottom of the animal scale, even this simplicity 

 becomes simplified, and all the phenomena of life are 

 manifested by a particle of protoplasm without a nucleus. 

 " What has been said of the animal world is no less 

 ti'ue of plants. Imbedded in the protoplasm at the 

 broad, or attached end of the nettle hair, there lies 

 a spheroidal nucleus. Careful examination further 



