Chapter V — 33 — Physical Chemistry 



(CoMANDON and Pinoy, Seifriz, Mangenot) and the elastic 

 properties of the cytoplasm. 



Utilizing the results obtained from the study of protein solu- 

 tions, Mayer and Schaeffer with the ultramicroscope began the 

 study of animal cells living under favorable conditions. This study 

 permitted the authors to observe that the cytoplasm presents 

 in the ultramicroscope only a few lighted granules, which do 

 not show Brownian movement. They are not to be classed as mi- 

 celles for they are always visible in direct light. In addition to 

 these granules which belong to the paraplasm, the cytoplasm, 

 like the nucleoprotein solutions, does not show under the ultra- 

 microscope any visible micelle at all. Schaeffer, therefore, has 



Fig. 9. — Ultramicroscopic view of epidermal cells of the 

 leaf of Iris germanica. 1, In the living cell the nucleus is 

 opalescent, the nucleolus and cytoplasm optically empty. The 

 granules correspond to lipide inclusions either (P) within 

 invisible filamentous plastids or (GO dispersed in the cyto- 

 plasm. 2, In the coagulated cell the nucleus and cytoplasm are 

 entirely luminous. 



identified it with a fluid hydrogel. Now a fluid hydrogel behaves like 

 an electronegative hydrogel. Like all the alkaline or negative gels, 

 it becomes cloudy when it is put into acids : at first confused lumi- 

 nous streaks are seen, then ultramicroscopic granules which 

 soon become visible in direct lighting and assemble in a network. 

 Finally the cytoplasm becomes entirely luminous. It is then coagu- 

 lated. The salts of heavy metals and, in general, all substances em- 

 ployed as fixing agents, act in the same manner as acids, by making 

 the cjrtoplasm appear granular and vesiculate. The dehydrators 

 (alcohol, heat) act similarly. On the contrary, in the presence of 

 alkalis the cytoplasm remains optically empty. 



