ZOOLOGY AND BOTANY, MIOKOSCOPY, ETC. 69 



2. If their contact with the gas is not so long, say from one to 

 three days, they do not entirely lose the power of germinating ; the 

 embryo will begin to develope under normal conditions. 



3. A longer contact with the gas kills the cells. 



4. In a mixture of two parts by measure of nitrous oxide and one 

 part of atmospheric air, the power of germination of peas is very 

 greatly weakened. 



5. If peas have been made to germinate under ordinary conditions, 

 and then brought into pure nitrous oxide, no further development 

 whatever of the root and stem takes place. 



6. In pure nitrous oxide no geotropic or heliotropic curvatures 

 take place. 



7. Etiolated parts of plants do not become green in the light if 

 surrounded by an atmosphere of pure nitrous oxide. 



8. A number of experiments prove that vitally active cells are not 

 able to decompose nitrous oxide ; and that they therefore have no 

 power of using its oxygen for the purpose of respiration. 



Chlorophyll and the Cell-Nucleus.* — G. Schaarschmidt makes the 

 following observations : — 



1. Division of chlorophyll. The mode of division of the 

 chlorophyll-grains resembles that of the nucleus, and takes place 

 either directly by constriction, or indirectly by division with forma- 

 tion of threads. All green chlorophyll-grains divide in one or other 

 of these ways, as does also the endochrome of diatoms, as, for example, 

 the coccochrome of Odontidium vulgare, and the placochrome of 

 Himantidium pectinale. 



2. Hypochlorin occurs also in the Cryptophycese and diatoms. 

 When Nostoc, Microcoleus, Merismopedium, and Oscillaria, had been 

 treated for two days with concentrated, and then for four days with 

 dilute hydrochloric acid, and preserved in it, three, four, or more 

 minute rusty-brown masses made their appearance on the surface of 

 the cells, which showed the characteristic properties of hypochlorin. 

 The endochrome of diatoms treated in the same way becomes dirty 

 green, and assumes a spongy structure, hypochlorin appearing at the 

 margins in the form of irregular brown masses. This occurred in 

 Cymatopleura Solla, Himantidium pectinale, Synedra splendens, Pinnu- 

 laria viridis, P. radiosa, &c., and especially in Synedra ulnce. The 

 reactions were not, however, successful in every individual. 



3. The cell-nucleus of Nostoc. A small round body was observed 

 in the cells of Nostoc, usually in contact with the division-walls, and 

 which showed beautiful phases in the division of the cells. When 

 the cell has elongated and is ready for division, this body parts in 

 the middle, a colourless central zone being thus formed in the midst 

 of the colouring substance. When oblong cells are placed in coloured 

 alcohol-material, the nucleus is constricted ; the constriction becomes 

 gradually deeper, and a furrow appears on the outside of the cell. 



* Schaarsclimidt, G., ' Morpliology of Chlorophyll and of the Vegetable Cell- 

 nucleus ' (in Magyar) ; with drawings and a photogram. 56 pp. Klauseuburg, 

 1881. See Bot. Centralbl., vii. (1881) p. 263. 



