ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 4T 



BOTANY. 



GENERAL, 

 Including: the Anatomy and Physiology of Seed Plants. 



Cytology, 

 including: Cell-Contents. 



Nuclei of Unicellular Animals contrasted with those of Plant 

 Cells.* — L. Feinberg shows that the nuclei of organisms such as Ammha y 

 Plasmodiophora, the malarial parasite, &c. exhibit a structure quite 

 different from that of the nuclei of ordinary animal and plant cells. 

 While the latter nearly always show a chromatin network, which with 

 the Romanowski stain becomes coloured red, and nucleoli which, like 

 the protoplasm, becomes coloured blue with the same stain ; the former 

 show merely a number of nucleoli, which, by the Romanowski method,, 

 stain red, not blue, and are surrounded, not by a chromatin network,, 

 but by a clear area which remains unstained and seems to represent cell 

 and sap. Feinberg concludes that, from their staining reaction, the 

 nucleoli of these animal-like unicellular organisms are comparable to the 

 staining network of ordinary animal and plant cells. 



Continuity of Protoplasm. f — H. Kraemer suggests that the appear- 

 ances described by Gardiner and others as indicating a continuity of 

 protoplasm through the cell-wall, are due to a peculiarity in the struc- 

 ture of the cell-wall, which is made manifest by the reagents employed, 

 and which bears an analogy to the structure of the starch-grain. He 

 cites observations which lead to the following interpretations. The 

 starch-grain and the cell-wall are made up of alternating lamellae of 

 colloidal and crystalloidal substances. Physically the structure of the 

 starch-grain and cell-wall are quite similar, although chemically dif- 

 ferent, the preponderating substance in the grain being granulose, while 

 in the cell- wall the fundamental substance is cellulose. The crystal- 

 loidal layer in the starch-grain, consisting chiefly of granulose, is 

 coloured blue with iodine or chlor-zinc iodide, whereas in the cell-wall 

 this layer, consisting chiefly of cellulose, is coloured blue only with 

 chlor-zinc iodide. The colloidal layers in both grain and cell-wall take 

 up various anilin dyes. In starch-grains, as in cell-walls, there are 

 radial clefts or colloidal areas, which, under certain conditions, also take 

 up various anilin stains. The peculiar biconvex arrangement of the 

 groups of striae between contiguous cells in Nux vomica and Phytelephas 

 is suggestive of fundamental lines of development corresponding to 

 chromatin threads, although they may be modifications of the wall and 

 represent tracts or channels through which liquids are distributed from 

 cell to cell. All authors since the appearance of Gardiner's work have 

 fallen into the error of supposing that a certain anilin dye could be 

 regarded as a differential stain for protoplasm, whereas many colloidal 



* Ber. Deutsch. Bot. Ges., xx. ri902) pp. 281-3.1 



t Proc. Amer. Philosoph. Boo., xli. (1902) pp. 174-80 (2 pis.). 



