ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 979 



BOTANY. 



A. GENEBAL, including- the Anatomy and Physiology 



of the Phanerogamia. 



a. Anatomy.* 



Q) Cell-stmcttire and Protoplasm. 



Morphological and Chemical Composition of Protoplasm.f — In this 

 very exhaustive treatise Herr F. Schwarz enters into great detail with 

 respect to the behaviour of the different constituents of the protoplasm of 

 the vegetable cell with various reagents ; only the more important results 

 can be indicated here. 



The varying acid or alkaline reaction of the cell-sap in different cases 

 he attributes to the pigments or other substances contained in solution in it ; 

 in no case has he found the protoplasm to have an acid, but in most cases 

 a distinctly alkaline reaction ; and this applies equally to the cytoplasm, the 

 nucleus, the chromatophores, and the microsomes, and in some cases also to 

 the protein-grains. This alkaline reaction is not due to the presence in the 

 protoplasm of ammonia or other free alkalies, but probably to alkaline salts, 

 especially phosphates, combined with the albuminoids in the living cell. 



The author regards the chlorophyll-bodies as having a fibrillar structure ; 

 the fibrillfe do not, however, form a network, but lie side by side, filling up 

 the entire mass of the chlorophyll-body. The fibrillee, composed of a sub- 

 stance which he calls chloroplastin, are not uniform in colour, but contain 

 globular bodies of a deeper green than the rest, the vacuoles or " grana " of 

 Meyer; between the fibrillEe is a colourless substance, the metaxin. These 

 two components of the chlorophyll-bodies can be separated by the action of 

 water, in which the fibrillte swell up strongly, but are entirely insoluble, 

 while the metaxin is finally completely dissolved. They may also be 

 distinguished by other chemical reactions. 



As components of the nucleus, Schwartz distinguishes the following 

 substances: — (1) chromatin, the portion most sensitive to staining, occurring 

 in the form of larger or smaller globules or granules, the " nucleo-micro- 

 somes" of Strasburger; (jT) py renin and amphipyrenin, which constitute, 

 respectively, the body and the membrane of the nucleus ; these differ widely 

 in their reactions from chromatin, and from one another, the former 

 taking up staining reagents much more readily; (3) linin and paralinin, 

 the substance respectively of the nuclear threads, the " nucleo-hyaloplasm " 

 of Strasburger, and of the intermediate matrix or " nuclear sap." The 

 behaviour of these various substances towards different reagents is given in 

 great detail. 



The cytoplasm has, as a rule, no reticulate or fibrillar structure ; though 

 in Spirogyra and some other cases a certain amount of differentiation does 

 occur. It is made up of three distinct substances : — the substances dissolved 

 in the vacuoles or cell-sap ; the microsomes, insoluble both in water and in 

 the cytoplasm ; and the mucilaginous constituent or cytoplastin ; this is the 

 only proteinaceous substance invariably found in the cytoplasm, except in 

 the youngest cells. The chemical properties of these various ingredients 

 are again gone into in great detail. The formation of vacuoles the author 

 regards as the result of the separation of substances previously combined, 

 the more soluble of these collecting in the form of drops within the less 



* This subdivision contains (1) Cell-stnicture and Protoplasm; (2) Other Cell- 

 contents ; (3) Secretions ; (4) Structtire of Tissues ; and (5) Structure of Organs. 

 t Cohn's Beitr. z. Biol. d. Pflanzen, v. (1887) pp. 1-214 (8 pis.). 



