THE PHENOMENA OF LIFE 



... Space contain- 

 ing liquid. 



Protoplasm. 



Nucleus. 



Cell wall. 



FIG. i. Vegetable Cells. 



gradually to be recognized as of primary importance. Many of the lower 

 forms of animal life, the Rhizopoda, were found to consist almost entirely 

 of matter very similar in appearance and chemical composition to the cell- 

 substance of higher forms; and this from its chemical resemblance to flesh was 

 termed Sarcode by Dujardin. When recognized in vegetable cells it was called 



Protoplasm by Mulder, while Remak applied 

 the same name to the substance of animal cells. 

 As the presumed formative matter in animal 

 tissues it was termed Blastema, and in the be- 

 lief that, wherever found, it alone of all sub- 

 stances has to do with generation and nutrition, 

 Beale has named it Germinal matter or Bio- 

 plasm. Of these terms the one most in use at 

 the present day, as we have already said, is 

 protoplasm, and inasmuch as all life, both in 

 the animal and vegetable kingdoms, is associated 

 with protoplasm, we are justified in describing 

 it, with Huxley, as the "physical basis of life," 

 or simply "living matter." 



Properties of Protoplasm. Protoplasm 

 is a semi-fluid substance, which absorbs but 



does not mix with water. It is transparent and generally colorless, with 

 refractive index higher than that of water but lower than that of oil. It is 

 neutral or weakly alkaline in reaction, but may under special circumstances 

 be acid, as, for example, after activity. It undergoes heat-coagulation at 

 a temperature of about 54.5 C. (130 F.), and hence no organism can live 

 when its own temperature is 

 raised above that point. It is 

 also coagulated and therefore 

 killed by alcohol, by solutions 

 of many of the metallic salts, by 

 strong acids and alkalies, and by 

 many other chemical substances. 

 Under the microscope it is 

 seen almost universally to be 

 granular, the granules consisting 



of different mibstanre<; albii- FIG. 2. Semidiagrammatic Representation of a Human 

 .CS, 1DU Ovum, showing the parts of an animal cell. (Cadia.) 



minous, fatty, or carbohydrate 



matter. The granules are not equally distributed throughout the whole 

 cell-mass, as they are sometimes absent from the outer part or layer, 

 and very numerous in the interior. In addition to granules, protoplasm 

 generally exhibits spaces or vacuoles, usually globular in shape, except- 

 ing during movement, when they may be irregular, and filled with a watery 



ger- 

 minal vesicle. 

 L Nucleolus or ger- 

 minal spot. 

 Space left by re- 

 traction of yolk. 



... Vitellus or yolk. 



Vitelline mem- 

 brane. 



