1 82 ROBERT H. BOWEN. 



blackened rim appears as a ring, while in profile it appears as 

 a rod, ellipses of varying size being apparently seen at inter- 

 mediate angles of vision. These platelets have now been demon- 

 strated with the greatest clearness in practically all the tissues 

 mentioned in this paper, and throughout the three higher plant 

 groups they appear to be a constant and characteristic part of 

 the cytoplasm. They are usually very numerous, sometimes 

 running into the hundreds, as in the large cells of the barley 

 root-tip. In general they are rather small (Fig. i) but they 

 tend to be larger in the root-cap cells of spermatophytes, and 

 less numerous and more conspicuous in the androgonia of 

 Polytrichum (Fig. 8). They show no peculiarities of distribution 

 in either the resting or dividing cell, except possibly a tendency 

 to heap up along the cell plate in the telophase of division. 

 They seem to multiply by a process of fragmentation, but 

 nothing very definite can be said on this point. Thus far they 

 do not appear to have any function capable of expression in 

 terms of their visible morphology, except in the moss androcyte. 

 The most extraordinary thing about these platelets is that 

 they are so readily demonstrable by the methods used for the 

 animal Golgi apparatus, but, with rare exceptions of a special 

 nature, can not be demonstrated by any of the usual staining 

 methods. It appears probable that these bodies as a permanent 

 and generalized component of plant cytoplasm have never been 

 described before, indeed may very probably never have been seen 

 by botanists. It is an extraordinary fact that Guilliermond 

 ('26) does not mention these platelets in his recent paper, and 

 the only explanation I can offer is that they have possibly been 

 mistaken for one of the other and well-known cytoplasmic 

 constituents. He has, in an earlier paper ('24), claimed that 

 plant cells in general contain lipoidal granules which he calls 

 the "granulations lipoides." These are granules, not platelets, 

 and they are easily demonstrated by osmic methods which do not 

 suffice for the osmiophilic platelets. I am, therefore, of the 

 opinion that these fatty granules of Guilliermond represent 

 exactly what he calls them, and that they have nothing to do 

 with the osmiophilic platelets here described. The lipoidal 

 granulations would appear to correspond roughly to the fatty 



