132 PLANT PHYSIOLOGY 



remains in obscurity. It is known that these are formed in both 

 non-chlorophyllous and chlorophyllous plants, and that while in the 

 former it may proceed in darkness, in the latter, light is apparently 

 required for the most vigorous synthesis. In the latter case it may 

 seem to suggest that there is need of the active cooperation of the 

 chlorophyll apparatus; but here again the influence may be only 

 indirect, since the roots, as well as the aerial parts of chlorophyll- 

 bearing plants, are said to possess, to a certain extent, this synthetic 

 power. Interesting suggestions have been recently made by God- 

 lewski. The part played in photosynthesis by nucleus and cytoplasm, 

 respectively, is unknown and may be important. 



Some careful studies have been made dealing with the sources 

 of organic nitrogen in certain of the molds, but owing to the very 

 great variety of fungous habitats, further studies may indicate 

 unusual specialization, perhaps even to such extent as is now 

 known to be true with the bacteria. 



Saida has confirmed and extended the early work of Puriewitsch 

 and others, clearly demonstrating that under certain conditions 

 some of the fungi are able to utilize to a variable degree the atmo- 

 spheric nitrogen. It would be interesting in this connection to give 

 further attention to various groups of saprophytic fungi. In a pub- 

 lic lecture Moore has recently made known the results of remark- 

 ably definite experiments showing that the organism (or organisms) 

 of leguminous tubercles assimilates free nitrogen apart from its 

 hosts, and that, therefore, the symbiotic association gives the para- 

 site no nitrogen-assimilating advantages. Moreover, this nitrogen- 

 assimilating capacity increases under conditions of artificial culture, 

 and this increased power is heritable to a considerable extent at 

 least. This is an important fact and deserves further attention. 



Recently Reinke, Benecke, and others have focused our atten- 

 tion upon the nitrogen supply in sea-water. They find that the 

 organisms Clostridium Pasteur ianum and Azotobakler chroococcum 

 are found in the ooze of sea-bottoms; and the suggestion is made 

 that the external but nevertheless close association of these micro- 

 organisms with certain marine alga? may explain the power of these 

 algse to grow so vigorously in situations in which they are found. 

 The nitrogen supply is probably one of the most important prob- 

 lems relating to the marine algae. It is to be borne in mind, however, 

 that the question of fundamental interest is always that of how 

 these micro-organisms are able to utilize the nitrogen which is ab- 

 sorbed in gaseous state. No such power is known among phanero- 

 gams. It has not yet been demonstrated to be possible with the 

 lower alg;e, and certainly none of the interesting results so far ob- 

 tained indicate that it is a very fundamental character of fungi 

 and bacteria. In this connection, perhaps, it may also be stated 



