ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 75 



BOTANY. 



A. GENERAL, including Embryology and Histology 

 of the Plianerogamia. 



Relations of Protoplasm and Cell-wall in the Vegetable Cell.* — 

 F. O. Bower considers that it has now been demonstrated with as 

 much certainty as is possible, by the use of microchemical and 

 staining reagents, that in certain cases, the number of which is now 

 constantly being increased, there is a direct connection between the 

 protoplasmic bodies on opposite sides of cell-walls, and that this con- 

 nection is established by means of fine strings of protoplasm which, 

 in the cases observed, run nearly transversely through the walls. 

 The question remains whether this is the only mode of permeation 

 of the cell-wall by protoplasm. The author cannot accept it as 

 proved as yet that any further permeation of the cell-wall by pro- 

 toplasm really exists, but he brings forward certain grounds for 

 regarding such a permeation as possible or even probable, taking into 

 account chiefly those phenomena observed in free cell-walls, in order 

 thereby to avoid any confusion with connecting strings, such as those 

 already proved to exist : — 



1. The strings already observed vary greatly in thickness, from 

 the well-marked to the undistinguishable ; thus we have evidence of 

 the existence of strings which would probably not have been re- 

 cognized were it not for comparison with other examples. Further, 

 it has been shown, in the author's paper on plasmolysis, that pro- 

 toplasm may be drawn out into strings so fine as to defy definition, 

 even by high powers of the Microscope ; thus there can be no objec- 

 tion on the ground of the small size of the hypothetical strings or 

 reticulum. 



2. Those cases in which a perforation of cell-walls has been 

 demonstrated are those very cases in which a most efficient physio- 

 logical connection is required. There is no reason why a less obvious 

 permeation should be denied where the requirements are less, but by 

 no means absent. 



3. There is a priori probability of some form of permeation of 

 cell-wall by protoplasm, if Strasburger's account of the growth of 

 cell- walls be correct. 



4. A strong argument in favour of such general permeation of 

 walls by protoplasm is found in the existence of important chemical 

 changes in the substance of certain cell-walls at points at a consider- 

 able distance from the main protoplasmic body, e. g. formation of 

 cuticular substance, wax, &c., which differ fundamentally from cellu- 

 lose, are insoluble in water, and are apparently formed in the wall 

 itself. The tendency of recent observations is to show more and 

 more clearly how close the connection of protoplasm with the im- 

 portant chemical changes in the plant is ; thus it appears probable 

 that protoplasm is present in some form or other in the cell-wall. 



* Proc. Brit. Assoc. Adv. Sci., 1883, p. 581. Cf. this Journal, iii. (1883) 

 pp. 225, 524, 677. 



