THE LOCALIZATION OF PROTEID-SYNTHESIS 409 



the points at which such synthesis is active '. On the other hand, when ammonium 

 chloride is assimilated, the liberated acid must be neutralized. 



SECTION 72. The Localization of Proteid-synthesis. 



Since the assimilation of nitrogen compounds and the synthesis of 

 proteids proceed in fungi in the absence of light and chlorophyll, it can 

 hardly be doubted that these processes take place in chlorophyllous plants 

 also by means of chemosynthesis (cf. Sect. 68). In more highly organized 

 plants, however, it is probable that all the cells and organs do not take 

 the same part in the assimilation of nitrogen-compounds ; indeed in the 

 higher plants it is the leaves and chlorophyllous organs which in general 

 seem to be of especial importance in this respect. The roots, however, 

 seem also able to assimilate nitrates, and apparently they often form 

 proteids from the amides which are conveyed to them. It is not yet certain 

 whether any cells are present in the plant which have lost the power 

 of assimilating nitrogen-compounds to such an extent that, like an obligate 

 peptone- organism, they can live only when supplied with soluble proteids. 

 Moreover it is still unknown whether amides or proteids are principally 

 formed in green leaves. 



It has yet to be determined what are the respective parts which the 

 nucleus 2 and cytoplasm play in nitrogenous assimilation, and whether 

 this process occurs in the chloroplastids as well. Even though this should 

 prove to be the case it does not follow that the chloroplastids are organs 

 specially adapted for this purpose, for it may also take place in non- 

 chlorophyllous cells. Moreover, since nitrogenous assimilation continues 

 in green cells even in darkness, it follows that the direct action of light is 

 unnecessary 3 . It is true that in certain plants the formation of proteids is 

 favoured by exposure to light, but it does not follow that the energy of 

 the light-rays is directly used in effecting proteid-synthesis. Indeed it is 

 much more probable that in all cases the process is a chemosynthetic one 4 . 



1 Schimper, Bot. Zeitung, 1888, p. 97, and Flora, 1890, p. 231. On the relations of calcium 

 oxalate to the formation of proteids, cf. Holzner, Flora, 1867, p. 497 ; de Vries, Landw. Jahrb., iSSi, 

 Bd. x, p. 77. 



2 Haberlandt ascribes on insufficient grounds a special activity to the nucleus (Function u. Lage 

 d. Zellkernes, 1887, p. 116). 



3 Kosutany, Versuchsst., 1896, Bd. XLVIII, p. 13. Cf. Sect. So. The recent works of Laurent 

 (Bull. d. 1'Acad. roy. d. Belgique, 1896, iii. ser., T. XXXII, p. 815) and Godlewski (Anzeiger d. 

 Akad. d. Wiss. z. Krakau, 1897, p. 104) show that light, and especially certain rays, favour the 

 synthesis of proteids, but leave it undetermined whether the light directly affords the necessary energy 

 or only acts indirectly. On the other hand, Hansteen (Ber. d. Bot. Ges., 1896, p. 362) has shown 

 that Lemna can form proteids in darkness. 



* It is not easy to see why Schimper (Flora, 1859, p. 256) holds that the results obtained with 

 fungi do not afford any criterion as to what goes on in phanerogamic plants ; see also Chrapowicki, 

 Bot. Centralbl., 1889, Bd. xxxix, p. 352. 



