478 SUMMARY OF CURRENT RESEARCHES RELATING TO 



exhibiting similar changes. The feeding of the leaf is almost always 

 accompanied by an excretion of mucilage from the epiderm. 



Effect of Cold on the Nucleus.*— MM. L.Matruchot and M. Molliard 

 describe the effect produced by cold on the nucleus of the parenchy- 

 matous cells of the leaves of Narcissus Tazetta. The phenomena may 

 be compared, in general terms, to those of karyokinesis. In the first 

 stage the meshes of the network become larger and the filaments thicker ; 

 the chromatin accumulates at the nodes of this network. The nucleus 

 has a tendency to become bipolar, and the filaments of the chromatic 

 network to place themselves in a direction parallel to a line connecting 

 the poles. At a later stage a continuous equatorial ring is formed of 

 uniform breadth ; there is at this stage no trace of a nucleole. A sub- 

 sequent stage is characterised by the formation of a number of proto- 

 plasmic vesicles. 



C23 Other Cell-Contents (including' Secretions). 



Structure of ChlorophylLf — According to Herr G. Bode, chloro- 

 phyll grains contain a lecithin-compound (glycerin phosphate, cholin, 

 fatty acids), with which is combined the magnesium salt and a phyto- 

 sterin. The magnesium compound is fully developed only in full light. 

 The chlorophyll, which can be isolated from the lecithin-compound by 

 the action of potash-lye or sulphuric acid, can enter into combination 

 on the one hand with the alkalis, alkaline earths, and metals, on the 

 other hand with hydrochloric, phosphoric, or sulphuric acid. Phyllo- 

 xanthin is merely a mixture of various components of the lecithin-com- 

 pound with chlorophyllar and yellow pigments. 



Structure of Starch-grains. J — Mr. H. Kraemer claims to have 

 determined, from treatment with iodine and anilin pigments, that the 

 layers in a starch-grain consist of a substance rich in colloids but poor in 

 crystalloids, alternating with a substance rich in crystalloids but poor 

 in colloids. 



Proteinaceous Substances in Seeds. § — Dr. Th. Bokorny thus sums 

 up the present state of our knowledge on this subject : — The pro- 

 teinaceous substances soluble in a 5-10 per cent, solution of sodium 

 chloride (globulins) are stored up in the protein-grains and albumen- 

 crystals of seeds. The protein-grains (also known as aleurone-grains) 

 vary in size from 1 to 55 fx ; they attain the largest size in oily 

 seeds ; in the endosperm of cereals they are very small, but are never 

 absent. The presence of active protein could never be detected in the 

 grains. The fibrin (Kleberstoff) of cereals is a quite peculiar substance. 

 It is soluble in 70-80 per cent, cold or hot alcohol, a reagent which 

 precipitates other proteinaceous substances. The author was unable to 

 detect any pepton, at least in dormant seeds ; propeptons or albumoses 

 are occasionally found in very minute quantities. Simple amido-sub- 

 stances, asparagin, tyrosin, leucin, &c, are very widely distributed in 

 seeds and the vegetative parts of plants ; they appear to be the first 



* Comptes Rendus, exxx. (1900) pp. 788-91. 



t ' Unters. ub. d. Chlorophyll,' Cassel, 1898. See Bot. Centralbl., lxxxii. (1900) 

 ,) 51 X Bot. Gazette, xxix. (1900) p. 139. 



§ Bot. Centralbl., lxxxii. (1900) pp. 289-300. 



