ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 773 



BOTANY. 



GENERAL, 



Including- the Anatomy and Physiology of Seed Plants. 



Cytology, 

 Including: Cell-contents. 



Permeability of Protoplasm.*— J. Sziics has investigated the per- 

 meability of protoplasm as shown in the absorption of anilin dyes by 

 the living cells and the retardation of snob absorption by electrolysis. 

 The present investigations show that the rapidity of absorption of many 

 basic colouring matters is directly proportional to the concentration, but 

 the permeability of the plasma-membrane is not constant. Certain 

 electrolytes retard the absorption of basic colouring matters, the retarda- 

 tion being directly proportional to the valency of the kations. Dilute 

 solutions are proportionally more powerful than strong ones ; one and 

 the same amount of the electrolyte always produces the same retardation 

 with similarly concentrated solutions of the colouring matter. Calcium 

 salts and other electrolytes likewise retard the absorption of ferrous sul- 

 phate. The absorption of basic colouring matters is retarded by the 

 presence of acid colouring matters in accordance with well-defined laws. 

 The retardation caused by electrolytes is due to their effect upon the 

 plasma, while that produced by acid colouring matters is due to the 

 formation of a salt to which the plasma-membrane is impermeable. 



Formation of Chloroleucites.f — A. Guilliermond, in studying the 

 germination of barley, has found all stages of transition between chon- 

 driocontes and chloroleucites, and is of opinion that the latter owe their 

 origin to the former. In the basal, more rudimentary parts of the 

 seedling, the chondriocontes occur in vacuoles in the neighbourhood of 

 nuclei, and when cell-division occurs they are equally distributed among 

 the daughter-cells. Higher up they are changed in form, and are con- 

 fined almost exclusively to the neighbourhood of the nuclei ; as they 

 pass higher they become ovoid, and increase in size. From this point on- 

 wards the chondriocontes disappear, and only chloroleucites are found, 

 which occupy the same places, have the form of disks of spheres, and 

 are uniformly coloured or with light centres. Later on the chloroleucites 

 acquire their normal shape, size, and colour. If this discovery proves 

 to be correct, it is important, because it explains the origin of the 

 chloroleucites and the function of the chondriocontes. 



Mitochondries of Plant-cells.:}: — The same author contributes a short 



note dealing with his investigations concerning the presence and function 



* SB. Akad. Wiss. Wien, cxix. 7 (1910) pp. 737-73 (4 figs.). 

 t Comptes Rendus, cliii. (1911) pp. 290-2 (12 figs.). 

 j Comptes Rendus, cliii. (1911) pp. 199-201 (4 figs.). 



