78 COMPARATIVE ANATOMY 



of cellulosity, but it is nevertheless organised, since it emitj 

 diverse prolongations carrying granules with them, extending 

 and retracting themselves alternately in a word, it has life." 



The word " protoplasm" is due to a botanist, Hugo von 

 Mohl, who, in 1846, described the constitution of the so-called 

 primordial utricle in plant cells a semi-fluid, gelatinoid, 

 living substance, similar to the sarcode already described by 

 Dujardin. But, curiously enough, the identity between the 

 sarcode of animals and the protoplasm of plants, does not 

 seem to have struck the physiologists of the time. One 

 distinguished anatomist, Robert Remak, did indeed perceive 

 the identity between them, and applied the term protoplasm to 

 the substance composing animal cells, but his example was 

 not generally followed, and it was not until 1861 that the 

 modern conception of protoplasm was expounded by Sigis- 

 mund Max Schultze, to whom also we owe the definition of 

 a cell as given above " a corpuscle of protoplasm' within which 

 lies a nucleus " (Ein Kliimpchen Protoplasma, in dessen 

 Innerem ein Kern liegt). 



Max Schultze showed by means of many beautiful and 

 convincing experiments, the identity in the behaviour of the 

 protoplasm of plants and animals ; that both consist of a 

 hyaline, contractile, jelly-like ground substance containing 

 minute granules; that in both animals and plants the 

 granules may be seen to be in constant movement, streaming 

 in definite courses through the ground substance ; that the 

 effects of heat, electric stimulus, and chemical action are the 

 same in plant as in animal protoplasm. 



But still the term protoplasm has remained vague, and 

 several rival theories as to its constitution have been put 

 forward. The name itself has become too general, and 

 though it remains in use, it is on the tacit understanding 

 that it means the substance of the cell-body of such primitive 

 cells as we call undifferentiated. The cell-body of the 

 leucocyte is a good instance of what is meant ; but nowadays 

 it is usual to refer to the material of the cell-body as cytoplasm, 

 and to that of the nucleus as nucleoplasm, it being understood 

 that neither of them are homogeneous chemical compounds 

 of definite formula, but mixtures of several different kinds of 

 albuminous bodies, each of great molecular complexity. 



We may regard the terms "protoplasm" and "cytoplasm" 



