Guilliermond - Atkinson — 186 — Cytoplasm 



tory way. Either it excretes them into the vacuole or else it dies, 

 poisoned by them. It is only in products resulting from its metabo- 

 lism that the stains accumulate. We are thus brought back to 

 the idea expressed by many cytologists, VON MoLLENDORFF among 

 others, that vital dyes normally stain only that which we call the 

 deutoplasm, or paraplasm, m which are grouped all the products 

 arising from protoplasmic elaboration. The vacuoles belong in 

 this category and perhaps it would be suitable to include under 

 the general heading of vacuolar system (a term preferable to that 

 of vacuome, which involves the idea of morphological entity) all 

 the paraplasmic colloidal inclusions of the cytoplasm which are 

 not of a lipide nature or, at least, in which the lipides do not consti- 

 tute the essential element. These inclusions are composed of aque- 

 ous solutions of colloidal substances elaborated by the cytoplasm, 

 not miscible with it (doubtless forming a coacervate system sepa- 

 rate from the cytoplasm) and are characterized by a more or less 

 high concentration. They are however capable under certain physi- 

 cal conditions and in certain cells, by reason of their capacity for 

 taking in water which is stronger than that of the cytoplasm and 

 often unlimited, of becoming dilute and of taking on the aspect of 

 liquid inclusions or true vacuoles. In a word, the liquid vacuole 

 according to this interpretation may be formed each time that 

 there is deposited in the cell a product of secretion in a colloidal 

 state more capable of absorbing water than is the cytoplasm. So 

 the vacuolar system expresses a physical state, an aqueous phase, 

 separated from the cytoplasm, and containing various more or less 

 concentrated, colloidal and crystalloid substances of paraplasm 

 which may, according to the nature of these substances and the 

 conditions of the cell, have a rather high viscosity and which are 

 able to pass from the liquid to the semi-fluid or solid state. 



If, in the great majority of plants, the vacuolar system appears 

 to us as a morphological entity, it is undoubtedly because plant 

 cells undergo a considerable hydration, and because, from the first 

 stages of their development, the paraplasmic inclusions whose en- 

 closed colloids take up water, are transformed into liquid vacuoles, 

 which run together very quickly and become a single and enormous 

 vacuole in differentiated cells. It follows logically that all the 

 products of metabolism capable of forming solutions or pseudo- 

 solutions with water would collect in this single vacuole. In some 

 lower plants and in animals, on the contrary, the cells would not 

 undergo this hydration and the paraplasmic inclusions would gen- 

 erally remain in the cytoplasm as concentrated colloidal solutions, 

 making a distinction among them more easy by reason of the 

 chemical contents characteristic of each. 



According to this hypothesis it is possible to see, as does Mange- 

 NOT, a similarity between the vacuolar system and the lipide inclu- 

 sions — paraplasmic formations capable occasionally of being 

 stained in the living state because the vital stains are soluble in 

 lipides. In these inclusions, which are formed of neutral fats and 

 which are found in practically all cells, there accumulate all the 



