Sec. 6. Protoplasm 



Protoplasm is an albuminoid substance, ordinarily 

 resembling the white of an egg, consisting of carbon, 

 oxygen, nitrogen, and hydrogen in extremely complex 

 and unstable molecular combination, and capable, un- 

 der proper conditions, of manifesting certain vital 

 phenomena, as spontaneous motion, sensation, assim- 

 ilation, and reproduction, thus constituting the phys- 

 ical basis of life of all plants and animals; sarcode. 

 It is essential to the nature of protoplasm that the 

 substance consist chemically of the four elements 

 named (with or without a trace of some other ele- 

 ments) ; but the molecule is so highly compounded that 

 these elements may be present in somewhat different 

 proportions in different cases, so that the chemical 

 formula is not always the same. The name has also 

 been somewhat loosely applied to albuminous sub- 

 stances widely different in some physical properties, 

 as density or fluidity. Thus the hard material of so- 

 called vegetable ivory and the soft body of an amoeba 

 are both protoplasmic. The physiological activities 

 of protoplasm are manifested in its irritability, or 

 ready response to extenal stimuli, as well as its in- 

 herent capacity of spontaneous movement and other 

 indications of life; so that the least particle of this 

 substance may be observed to go through the whole 

 cycle of vital functions. Protoplasm builds up every 

 vegetable and animal fabric, it is itself devoid of dis- 

 cernible histological structure. It is ordinarily color- 



