2 PROTOPLASM 



Four years later, in 1839, the Bohemian physiologist Purkinje 

 first used the word "protoplasm" to describe the living substance 

 composing animal eggs and embryos. The German botanist 

 von Mohl applied the word to the living substance in plant cells 

 and showed that the ''sarcode" of animal cells and the proto- 

 plasm of plant cells are essentially the same. Von Mohl char- 

 acterized protoplasm as "niemals einen klaren wasserigen 

 Zellsaft . . . sondern . . . eine zahfliissige . . . Masse." While 

 opinions differ somewhat, it is still held by the great majority of 



Fig. 1. — The naked protoplasm, or Plasmodium, of a myxomycete (slime mold). 



workers that protoplasm is what Dujardin and von Mohl said it 

 was — a jelly, usually soft or fluid rather than firm though often 

 tough and highly elastic, glutinous and fibrous, and taking up 

 water with avidity. 



The most extraordinarily intrinsic quality of protoplasm is its 

 apparent and, in part, actual uniformity wherever found. 

 Whether it is the protoplasm of the petal of a flower or of the 

 muscle of an animal, it looks very much the same. Profound 

 differences must, of course, exist; otherwise, why should one cell 

 grow into a frog, while another very much like it in superficial 

 appearance grows into a tree? The most fundamental differ- 

 ences in protoplasm are wholly hidden from us, but other differ- 

 ences less significant, yet often very characteristic, are evident. 

 These latter have to do chiefly with such properties as con- 



