Guilliermond - Atkinson 



130 — 



Cytoplasm 



always appear in much smaller numbers than when obtained by 

 vital staining or after fixation. These bodies, therefore, are gen- 

 erally the result of flocculation of a substance found normally in a 

 colloidal solution in the vacuolar sap. This flocculation occurs in 

 the presence of vital dyes or fixatives. P. A. Dangeard kept for 

 this substance the name metachromatin which we had pro- 

 posed to designate the substance constituting the metachromatic 

 corpuscles (volutin of ARTHim Meyer). 



P. A. Dangeard had the idea of trying the effect of vital stains, 

 among others cresyl blue, on a very large number of cells of the 

 most varied plant groups. In every one he found that there existed 

 a colloidal substance dispersed in the vacuolar sap possessing a 

 strong capacity for taking up vital stains which precipitate it in 

 the form of corpuscles showing Brownian movement. These he 

 identified with the metachromatin of fungi. Thus he arrived at the 

 conclusion that all vacuoles enclose metachromatin, a specific sub- 

 stance of vacuoles, and he states that vital staining thus constitutes 



a property of the vacuoles 

 which is both general and 

 characteristic. 



Studying the origin of 

 vacuoles in most varied 

 plant cells by staining them 

 with the vital dye, cresyl 

 blue, Dangeard demon- 

 strated that vacuoles exist 

 in all embryonic cells but 

 are very different in ap- 

 pearance from ordinary 

 vacuoles. They are seen 

 here as numerous minute 

 elements composed of a very concentrated solution of metachro- 

 matin in a semi-fluid state. By their forms, as well as by their 

 dimensions, they are decidedly reminiscent of the chondriosomes. 

 It is these elements, swelling by imbibition and coalescing, which 

 finally become the large vacuoles characteristic of mature cells. 

 We shall not dwell on this matter here, but will study it later in 



more detail. 



Our research immediately afterward, confirmed, in part, the 

 facts observed by P. A. Dangeard. We recognized that the meta- 

 chromatin of fungi is normally found in a colloidal solution in 

 vacuoles. Vital dyes, for example neutral red, precipitate this 

 substance as corpuscles, intensely stained and showing Brownian 

 movement in the vacuolar sap which either remains colorless or 

 takes a diffuse stain. We also found, by using vital dyes in the 

 most diverse plant cells, that colloids are present as precipitable 

 pseudosolutions. Contrary to Dangeard's opinion, our work 

 showed, as we shall see further on, that the colloidal substances 

 contained in the vacuoles are of very different chemical natures and 

 do not show in the higher plants, nor even in many of the lower 



Fig. 83. — Saccharomyces eerevisiae. Precipitation 

 of metachromatin corpuscles (CM) in vacuole: 1, 

 by neutral red; small vacuole at right contains one 

 corpuscle. 2, haematein, after fixation with formol; 

 GL, very refractive lipide granules. N, nucleus. 



