Guilliermond - Atkinson — 212 — Cytoplasm 



appearance and the phenomena which accompany it, /liust take 

 place very quickly, and generally escape notice, for here we are 

 dealing with disturbed equilibrium which is, of necessity, tempo- 

 rary. In an attempt to avoid this difficulty and find out what 

 occurs at the moment when the parasite exerts its disorganizing 

 action, Beauverie experimented with various substances which act 

 upon living tissue (notably anisotropic solutions and certain sub- 

 stances such as saponin, which lowers the surface tension, choles- 

 terol and ether which modify the water content of the plastids, 

 etc.). He observed particularly the effects produced on the plastids 

 and chondriosomes. Among his results we find that the chloro- 

 plasts may degenerate by spreading out and fusing or, under other 

 conditions, may swell into relatively enormous vesicles which the 

 green pigment covers like a cap. These phenomena may or may 

 not be accompanied by lipophanerosis. 



Beauverie tried to show that in certain cases of parasitism the 

 plastids have a tendency to become more fragile (fragilization) 

 which is manifested by their greater sensitivity to anisotonic action. 

 This must be a condition preceding their disappearance in the para- 

 sitized cell. This diminution of resistance in the plastids in some 

 pathological states brings to mind observations made on blood glob- 

 ules under similar conditions (hemolysis). 



Beauverie and other writers have also found a fatty degenera- 

 tion of the plastids, analogous to that observed in the natural de- 

 generation of cells of some plants (Iris discussed above). Vesicu- 

 lation of the chondriosomes was also observed. 



In all cases in which parasitisms has an exciting action on the 

 tissues of the host, this action seems to be manifested by an exag- 

 gerated activity of the plastids, if we may judge from the similar 

 results of various investigations on the subject. 



Several authors, LjUBiMENKO, DucoMET, MoRQUER, Beauverie, 

 Miss Ruth Allen, and Dufrenoy, have cited cases in which the 

 parasite not only does not bring about a degeneration of the chloro- 

 plasts, but can induce manifestations of super activity, for ex- 

 ample, the production of starch more intensely in the parasitized, 

 than in the healthy, portion of the tissue. The research of Du- 

 frenoy on a certain number of diseases seems to show that para- 

 sites have an exciting action on the tissues of the host which is 

 manifested by an exaggerated plastidial activity. There may be a 

 superabundance of starch which results in a rather considerable 

 increase in leucoplasts. These investigations also show us that 

 fungal parasites exercise an action on the vacuoles of the host 

 which, in cells neighboring on the regions infected, frequently 

 modify their appearance : the large vacuoles break up into numer- 

 ous minute, filamentous, and reticulate vacuoles, analogous to those 

 observed in embryonic cells. This would seem to indicate an in- 

 tense secretory activity, facilitated by the increase of surfaces 

 of contact between the cytoplasm and the vacuolar contents. This 

 phase of hyperactivity seems to be followed, in those plants which 

 do not resist infection, by a phase of disintegration of the cyto- 



