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VACUOME 175 



led to much controversv. The older idea, due to von Mold 

 and others, claimed that they arose de novo in the cell. But as 

 far back as 1885, de Vries disagreed with this view, and advanced 

 the opinion that vacuoles were formed from certain bodies, to 

 which he gave the name '• tonoplasts.^^ To settle these conflicting 

 opinions, Pfeffer put the matter to experimental test. He intro- 

 duced a crystal of asparagine into the plasmodium of myxomycetes 

 and found that membranes were formed round the resulting 

 droplets. He concluded from the results of his work that vacuoles 

 could arise de novo in the cell. Pfeffer's views about this matter 

 were very generally accepted up to recent times. Dangeard, 

 however, advanced the theory that the vacuolar system of the cell, 

 or as they preferred to term it, the vcicuovie, is a permanent 

 constituent of the cell. This view has been enthusiastically 

 supported by Guilliermond. 



These w^orkers have found in the Cyanophycese and bacteria 

 certain corpuscles which stain deeply with basic aniline dyes. 

 Similar bodies were also discovered in the fungi, and they were 

 always to be located in the vacuole. These corpuscles, termed by 

 Dangeard " metachromes," or " metachromatic corpuscles," are 

 supposed to result from the precipitation of the normal colloidal 

 constituents of vacuoles by intravitam dyes, and they are there- 

 fore thought to exist in the vacuole of the living cell in the sol state. 

 In the growing tips of the hyphse of either Saprolegnia or Mucor, 

 Dangeard observed that vacuoles first made their appearance as 

 small beads or grains which were to begin with, somewhat isolated, 

 and also as threads which later fused together to form a network. 

 These bodies closely resemble mitochondria, and are composed 

 of a thick metachromatin fluid or solution which stains readily 

 with cresyl blue. With the ageing of the hyphae, these thread-like 

 bodies swell as the metachromatin solution absorbs water and 

 become conspicuous vacuoles, w^hich eventually fuse to form 

 larger vacuoles. In the flowering plants, Dangeard found in the 

 vacuoles a certain substance which he claimed to be closely 

 related to metachromatin. This was thrown out of colloidal solu- 

 tion by the action of intravitam stains, taking the form of deeply 

 stained, rapidly moving corpuscles in the vacuoles, the bulk of 



