Guilliermond - Atkinson 



— 210 — 



Cytoplasm 



a tendency to fuse into large globules, while the substratum of the 

 plastid is reduced to a great number of small granules which 

 soon disappear. At the same time, the chondriosomes swell and 

 become vesicular, as do the lipide granules. Eventually there 

 persist in the cytoplasm only large lipide globules, produced by the 

 disorganization of the plastids. 



In the chlorophyll-containing tissue, these 

 globules appear green and in cells enclosing 

 xanthophyll they appear yellow, the pigments 

 having dissolved in the lipides during degenera- 

 tion. These modifications seem to be due to a 

 breaking down of the lipides in the lipoprotein 

 complex comprising the plastids (lipophanero- 

 sis). It is apparently phenomena of this same 

 order, produced in the cytoplasm itself, which 

 bring about the fatty degeneration so often found 

 in animal cells and in fungi. 



In other flowers (Gladiolus, tulip, Clivia), only 

 the vesiculation of the plastids and chondriosomes 

 is observed. The vesicles burst and disintegrate 

 into small refractive granules which are scattered 

 in the cytoplasm and do not reduce osmium. 

 There is no fatty degeneration. 



Alterations produced by various physical 

 agents:- Radiations of short wave length, ultra- 

 violet rays and X rays, as well as « particles 

 emitted by radioactive bodies, destroy living cells, 

 but this destruction, especially by X ray and « 

 particles is not instantaneous. It is, on the con- 

 trary, preceded by very complex phenomena con- 

 cerning which we have, as yet, very little pre- 

 cise knowledge. 



The action of ultraviolet rays and X rays on 

 dye: V, vacuole the morphological constituents of the cytoplasm 

 stained ^with^^neutrai |g recorded largely in the work of Nadson and 



his students Rochlin and Stern. These investi- 

 gations have used as subjects, various yeasts and 

 the epidermal cells of Allium Cepa. These work- 

 ers report in all cases that radiation produced 

 first an excitation of cytoplasmic activity. The 

 currents become more rapid, the cytoplasm forms amoeboid pro- 

 longations in the direction of the vacuole, causing it constantly to 

 be deformed. In the second phase, the vacuoles return to their 

 previous shape. At the same time, lipide droplets form in large 

 numbers in the cytoplasm, in the chondriosomes and in the plas- 

 tids. Finally, plasmolysis occurs and the cells soon die. 



Radium and its salts produce similar effects, as shown by Nad- 

 son and his followers, as well as by MiLOViDOV. These workers 

 have also studied the action of the radioactive salts on the chondri- 



FlG. 147. — Iris 

 germanica. Epidermal 

 cell of a leaf plas- 

 molyzed in a 5% 

 NaCl solution with 

 neutral red added. 

 Cell contents form a 

 large ball in the cen- 

 ter of the cell con- 

 nected to the wall by 

 slender threads which 

 are enlarged here and 

 there. Cv, bodies pre- 

 cipitated from the 

 colloidal contents of 

 the vacuole by the 



somes; M, mitochon- 

 dria; N, nucleus; Fm, 

 structures resembling 

 myelin figures pro- 

 duced from the cyto- 

 plasm. 



