CHAPTER II 



PROTOPLASM AND CELLS 



THE CONSTITUTION OF PROTOPLASM 

 —THE AMOEBA— TISSUES 



The remainder of the cell is more or less densely filled with an 

 opaque, viscid fluid, of a white colour, having granules inter- 

 mingled in it, which fluid I call protoplasm. 



* ^ ^ VoN MoiiL (1846). 



The Constitution of Protoplasm 



All living organisms are built up of protoplasm and its 

 products. Both plants and animals consist of this same pro- 

 toplasm, the "physical basis of life," as Huxley called it. All 

 modern evidence tends to show that protoplasm is an equi- 

 librium mixture of a fluid and of a more solid jelly. The relative 

 proportions of the liquid and the jelly are from time to time 

 chanoed. Manv cells are solidified at certain times to a his:h 

 degree; and the change from the more fluid state to the more 

 jellied state is reversible. Cells which are at one time very 

 fluid may at other times be very solid, and vice versa. For 

 instance, fertilization causes the protoplasm of the egg to 

 become less solid and more liquid. 



It is impossible to analyse by chemical or physical means 

 living protoplasm, for any attempt at such analysis at once 

 kills it. 



By the analysis of dead protoplasm we find it contains 

 ■proteins, and proteins are compound chemical substances 

 which are never found apart from living matter. They contain 

 carbon, hydrogen, nitrogen, oxygen and sulphur, and have 

 the following percentage composition: 



Carbon from 50 to 55 per cent. 

 Hydrogen ,, 6-5 ,, 7-3 ,, 

 Nitrogen ,, 15 „ 17-6 „ 

 Oxygen „ 19 „ 24 „ 



Sulphur „ 0-3 „ 2-4 „ 



The proteins are tremendously important, and play a most 

 prominent part in the building up of protoplasm. Proteins 



