278 COLLOIDS IN BIOLOGY AND MEDICINE 



mum, desmids, diatoms, oscillaria, etc.), yeasts, the common frog- 

 bit, vallisneria, and several mosses. 



GAIDUKOV comes to the following conclusion as the result of 

 these investigations: Protoplasm must consist of hy.drosols because 

 everywhere in living protoplasm he saw particles with Brownian 

 movement. Frequently he observed that the particles combined 

 or separated and that their number increased or diminished, phe- 

 nomena which in my opinion represented metabolic changes. In 

 some, usually in very well nourished cells, there were no movements, 

 which may be attributed to the fact that the distances between the 

 numerous particles were too small. 



A transition from sol to gel condition, i.e., the cessation of Brownian 

 movement, was not observed in normal living cells. The colloids of 

 plant protoplasm evidently consist of a reversible and an irreversible 

 portion. If a cell is injured so that protoplasm escapes, a portion 

 will expand in the water and ultimately be dissolved in it, whereas 

 other portions combine (precipitate). This was observed in living 

 and in dead protoplasm. The observation of O. NAGELI is analogous : 

 If we crush a root hair of hydrocharis in water under a cover glass, 

 clumps of protoplasm pass through the rent. They are immediately 

 surrounded by a membrane which is impermeable for dyes; i.e., they 

 are coagulated on the surface. There is formed at the site of the 

 wound an irreversible layer of hydrogel similar to the fibrin forma- 

 tion of higher animals. The ultramiscoscopic observations quoted 

 entirely confirm what was earlier observed when plant cells absorbed 

 water. For instance, if we place myxomycetes in water, they swell; 

 and in spite of the increase in surface, the outer hyaloplasm retains 

 its thickness. Evidently the entering water causes a gelatinization 

 of the granular plasma at the surface of contact, so that the hyalo- 

 plasm layer spontaneously supplements itself. 



W. W. LEPESCHKIN regards protoplasm as a loose combination of 

 proteins and lipoids which breaks down under lethal conditions 

 (coagulation). If I understand him correctly he does not assume 

 the existence of a plasma pellicle (see p. 245) but believes that all 

 the properties ascribed by other investigators to this membrane as 

 a limiting surface should be attributed to the protoplasm as a whole. 



It must be remembered that all these observations experience 

 certain limitations depending on the kind and the part of the plant 

 involved. As a result of his experiments with sunflower seedlings, 

 BOROWIKOW assumes that plasma exists in seeds and spores as a 

 solid phase which changes to the gel condition in resting plants 

 (evidently jellies are meant). 



In the growth period, the plasma as the result of hydration exists 



