62 BOTANICAL GAZETTE. [ March t 



those who consider the protoplasm as a gelatinous mass, in 

 which here and there some bodies, such as a nucleus and 

 plastids, are imbedded, and he calls the protoplast an ele- 

 mentary organism, composed of several organs, which stand 

 in some respects in the same relation to each other as the 

 organs of a multicellular plant. There is, however, one pe- 

 culiarity in the organization of the protoplast, which is that 

 its organs always derive their origin from similar organs. 

 As far as is now known, they never appear in a protoplast 

 which has not received them from its ancestors, and if a pro- 

 toplast afterwards contains more organs of the same sort than 

 it did when young, these are formed by repeated divisions. 

 It may be said, with perfect truth, that the organization of 

 protoplasts is a visibly hereditary one. 



These views, of which I can only give a very short account, 

 are discussed here in detail, as recent discoveries, partially 

 made under the auspices of Prof, de Vries himself, have 

 contributed much to confirm them. As for the nucleus, it is 

 now generally known that this must be a very important or- 

 gan, that it propagates itself by division, and never appears 

 except where this has taken place. The same has been 

 proved for plastids by Schmitz, Schimper and Arthur Meyer. 



By Prof, de Vries himself it has been shown that vacu- 

 oles have a wall of living protoplasm, which can easily be 

 separated from the other parts of the protoplast. He has 

 called this wall " tonoplast," and has conclusively shown 

 that it must be considered also as a separate organ, in all 

 probability for producing cell-sap. Now the question re- 

 mained, whence did the protoplast derive its tonoplasts and 

 vacuoles, and this has been solved by Went, who has found 

 that all vegetable cells, even the very youngest, contain 

 vacuoles ; that they can divide themselves or be divided, and 

 thus multiply ; and that in those cases in which formerly the 

 appearance of vacuoles in homogeneous protoplasm was* 

 assumed, they are already present, but have been hitherto 

 overlooked. 



Another of Prof, de Vries's pupils, Wakker, has found that 

 the so-called aleurone-grains are nothing else than the dried 

 up albuminous contents of vacuoles in seeds, and that crys- 

 tals in living cells are formed within the vacuoles. 



Thus the whole protoplast appears as an organized indi- 

 vidual, with its nucleus, plastids (which in many cases form 

 starch), and tonoplasts (always containing cell-sap, often 

 crystals or aleurone-grains). In the remaining part of the 



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