98 THE CELL DOCTRINE. 



rather than in principle from that of the protoplasm 

 of the nettle. Under sundry circumstances the cor- 

 puscle dies, and becomes distended into a round 

 mass, in the midst of which is seen a smaller spheri- 

 cal body, which existed, but was more or less hid- 

 den, 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 framework of the 

 body. Nay, more; in the earliest condition 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 cor- 

 puscles, 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 mul- 

 tiple of such units; and, in its perfect condition, it 

 is a multiple of such units, variously modified." 

 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 nu- 

 cleus. There are sundry very low animals, each of 

 which, structurally, is a mere colorless blood cor- 

 puscle, leading an independent life. But, at the very 

 bottom of the animal scale, even this simplicity be- 



