CHAPTER II 



SOME PHYSICAL PROPERTIES OF THE PROTOPLASM 

 OF THE PROTOZOA 



H. W. Beams and R. L. King 



Introduction 



DujARDiN in 1835, a little over a century ago, was the first to care- 

 fully describe the physical properties of protozoan protoplasm which 

 he termed "sarcode," although other earlier observers had seen and 

 drawn living amoebae. For instance, Rosel von Rosenhof drew an amoeba 

 in 1755, O. F. Miiller described living amoeba in 1773 and Ehrenberg, 

 a pioneer protozoologist, undoubtedly observed living protozoan proto- 

 plasm. However, none of these observers emphasized the protoplasm as 

 the living substance as did Dujardin. In addition, Dujardin's description 

 of protoplasm was so accurate that his definition of it as a "living jelly, 

 glutinous and transparent, insoluble in water, and capable of contract- 

 ing into globular masses and of adhering to dissecting needles so that it 

 can be drawn out like mucus" can be little improved upon today (see 

 Faure-Fremiet, 1935). 



Perhaps no group of animals has served as the basis for so many 

 and so extensive studies on the structure of protoplasm as the Protozoa. 

 This is, no doubt, in part due to the fact that many of the earlier 

 workers labored under the assumption that the "simplest type" of proto- 

 plasm should be looked for in the "lower forms" of animals. In addi- 

 tion many of the Protozoa are comparatively large and discrete cells, 

 thus offering little mechanical difficulties to direct microscopic observa- 

 tions upon their living structure. 



In a modern discussion of the physical properties of protoplasm, one 

 must bear in mind the fact that the manifold chemical and physiological 

 properties of living matter are intimately connected with the structure of 

 protoplasm. That is, one must conceive of a system which is kept in 

 existence, in spite of the fact that the katabolic phases of energy ex- 

 change tend to destroy its integrity; this involves a continuous auto- 



