STRUCTURAL ELEMENTS OF THE CYTOPLASM. 187 



is aroused that the reaction to osmic acid is largely a response 

 of the contents of the vacuole to osmic acid, the content- 

 responding positively or negatively according to its composition. 

 Thus some root-tips will respond, while in other plants the 

 results are negative or very indifferent. This should certainly 

 not be the case if the vacuome as a whole represents the Golgi 

 apparatus, and the conclusion certainly seems justified, that the 

 claims so far made are not in agreement with the known behavior 

 of osmic acid toward the animal Golgi apparatus. In a preceding 

 report (Bowen, '266) I inclined to the belief that the vacuolar 

 primordia had lipoidal affinities, possibly in the sense that the 

 vacuolar walls were lipoidal in nature. Such a view still seems 

 to me a possible one, and it would certainly make easier an 

 explanation of the results as a whole but whether or not such 

 an enveloping lipoid membrane occurs, can not now be finally 

 settled. Should such a membrane occur, it might be possible 

 to relate it to the Golgi apparatus, but as to the contents of the 

 vacuole, no relation with the animal Golgi apparatus itself seems 

 possible. 



The most complete results on the morphology of the vacuome 

 have been obtained on the root-tips of Vicia and Ricinus, 

 particularly the former. In the earliest meristem cells the 

 cytoplasm is crowded with many small, more or less spherical 

 vacuoles or vacuole primordia (compare Fig. 5, an older stage 

 in Ricinus}. In Vicia these vacuole primordia undergo rather 

 different histories in plerome and periblem. In the plerome, 

 the small vacuoles of the earliest stages gradually merge together 

 (Fig. 6), growing larger meanwhile, until the large vacuole 

 characteristic of plant cells emerges. All phases in the fusion 

 can be impregnated with unusual clarity in the periblem of 

 Ricinus. In the periblem of Vicia a remarkable network is 

 developed by transformation and fusion of the vacuole primordia 

 (Fig. 7), later passing on into the large single-vacuole condition. 

 In cell division (Fig. 7, left-hand cell, prophase), these networks 

 are frequently more or less fragmented, presenting a very charac- 

 teristic appearance. It is claimed by some who have seen my 

 preparations that such bizarre networks can not possibly be 

 normal, but the results of the Dangeards and particularly of 



