Guilliermond - Atkinson 



158 



Cytoplasm 



tv ■;.• 



myces Magnusii) a double vital staining of the chondriome and 

 the vacuolar system by means of using a mixture of a solution of 

 neutral red and Janus green or Dahlia violet. In this way, we were 

 able to follow the simultaneous development of the two systems 

 during the entire growth of the plant. The chondriosomes by this 

 method are colored green or blue and the vacuoles red. (Fig. 104) . 

 These initial forms of the vacuoles which look like chondrio- 

 somes, are very fragile, just as the chondriosomes are, and they 

 swell and fuse into larger spherical vacuoles during prolonged 

 observations with vital staining, but this alteration of shape has 

 nothing in common with the cavulation of the chondriosomes (c/. 

 p. 101). Solutions of osmic acid preserve and heavily blacken 



the chondriosome-shaped vacuoles whenever they 

 contain phenolic compounds; otherwise it may 

 preserve them in a greatly swollen condition 

 without blackening them. It is known that the 

 chondriosomes are, on the contrary, very well 

 preserved with osmic acid but are not darkened 

 by it. 



In preparations treated by mitochondrial tech- 

 niques, the chondriosome-shaped vacuoles usually 

 appear as uncolored canaliculi, sometimes anasto- 

 mosing in a network in the midst of the faintly 

 colored cytoplasm. Sometimes the contents of 

 the vacuole are colored, but this is rare. When 

 it does occur, however, they are always found 

 condensed by the action of the fixatives in the 

 middle of the colorless canaliculi so that it is not 

 possible to confuse the elements of the vacuolar 

 system with the chondriosomes. Sometimes also 

 the colloidal contents of large liquid vacuoles, de- 

 rived from the chondriosome-shaped vacuoles by 

 hydration, show bodies precipitated by the action 

 of the fixatives which stain with mitochondrial 

 technique. (Figs. 105, 106). 

 In all cases in which the vacuoles contain tannins, the chon- 

 driosome-shaped vacuoles appear as filaments, or as a network, 

 somewhat dilated by fixatives and colored yellow by potassium 

 bichromate, or blackened by osmic acid, according to the method 

 employed. The large liquid vacuoles resulting from their fusion 

 show, with the same methods, either granular precipitations or 

 large corpuscles stained yellow by potassium bichromate or black- 

 ened by osmic acid. But there is no method, in most cases, which 

 makes it possible to stain the colloidal contents of the vacuoles 

 after fixation, when they do not contain tannins, unless, perhaps, 

 the Golgi methods which will be discussed later (Fig. 107 and 

 108). 



In most fungi and some algae, however, we have seen that the 

 colloidal substance of the vacuoles, or the metachromatin, made 

 insoluble and precipitated in the form of corpuscles by formalin 



Fig. 102. — Cera- 

 tium strictum. N, 

 nucleus; V, vesicle; 

 Vac, vacuoles. (After 

 Dangeard). 



