THE PHENOMENA OF LIFE 



Space contain- 

 ing liquid. 



Protoplasm. 



Nucleus. 



Cell wall. 



FIG. i. Vegetable Cells. 



smaller bodies or nucleoli. Such a definition applied admirably to most vege- 

 table cells, but the more extended investigation of animal tissues soon 

 showed that in many cases no limiting membrane or cell wall could be 

 demonstrated. 



The presence or absence of a cell wall, 

 therefore, was then regarded as quite a 

 secondary matter, while at the same time the 

 cell substance came gradually to be recog- 

 nized 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 chem- 

 ical composition to the cell substance of 

 higher forms; and this from its chemical 

 resemblance to flesh was termed Sarcode 

 by Dujardin. When recognized in vege- 

 table 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 belief that, wherever found, it alone of 

 all substances has to do with generation and nutrition, Beale has named 

 it Germinal matter or Bioplasm. 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, 



i <k i -11 P IT )> /^i^S^SwSSBSSS^ilK Nucleus or ger- 



as the "physical basis of life," .K^BV-- minai vesicle. 



! 



or simply "living matter." 



General Physical a n d 

 Chemical Properties of Pro- 

 toplasm. Protoplasm is a 

 semifluid substance, which ab- 

 sorbs, but does not mix with 

 water. It is transparent and 



generally colorless, with refrac- FlG - 2. Semidiagrammatic Representation of 



, a Human Ovum, showing the parts of an animal 

 tive index higher than that of ce \\ m (Cadia.) 



water, but lower than that of oil. 



It is neutral or weakly alkaline in reaction, but may under special cir- 

 cumstances 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 



minal spot. 

 ----Space left by re- 

 traction of yolk. 



Vitellus of yolk. 



Vitelline mem- 

 brane. 



