848 EXPERIMENT STATION RECORD. 



11, p. 121). On account of the importance of this plant and the fact that it ig, 

 through its root tubercles, an active assimilator of nitrogen, studies were begun with 

 it in 1897 and continued with various interruptions for several years. 



The experiments, which are described in detail, show that sugar, most probably in 

 the form of glucose, is indispensable to the formation of hydrocyanic acid in the 

 leaves of P. lunatus, and evidence is produced showing that nitrates exert a direct 

 influence on the production of hydrocyanic acid. The author, summarizing his 

 work, again declares that hydrocyanic acid is the first recognizable product of the 

 assimilation of nitrogen in the leaves of P. lunatus. 



The assimilation of leucin and tyrosin by plants, L. Lutz {Bui. Soc. BoL 

 France, 52 {1905), No. 2, pp. 95-101, fig. 1).— In a previous publication (E. S. R., 

 11, p. 316) the author stated that phanerogams could not assimilate leucin or tyrosin 

 as their only sources of nitrogen. The frequent occurrence of these substances in 

 seeds and the experiments of others have led to a repetition of the author's studies 

 along this line. 



Experiments are reported with cucurbit seedlings and a number of molds in solutions 

 containing leucin and tyrosin as the only sources of nitrogen. Where leucin was 

 added to the culture medium, gains of 35.8 to 40.8 per cent in nitrogen are reported 

 for the cucurbits, while for tyrosin a gain of 11.9 per cent is given. Spores of Asper- 

 gillus and Penicillinm sown in culture media made excellent growth, showing that 

 both phanerogams and fungi can use these organic compounds as sources of nitrogen. 

 For the fungi they are about equally efficient, but for the flowering plants leucin, 

 being more soluble, is much 1 tetter assimilated than tyrosin. 



The assimilation of organic nitrogenous substances by plants, L. Lutz 

 {Bui. Soc. Bot. France, 52 {1905), No. 4, ]>]>■ 194-202).— A summary is given of the 

 investigations of the author and others on the assimilation of organic nitrogenous 

 compounds by plants, many of the more important papers having been noted else- 

 where (E. S. R., 8, p. 843; 10, pp. 235, 414; 11, p. 316; 14, pp. 119, 422). 



In all the author's experiments the flowering plants were grown in sand or similar 

 cultures, the seed being first sterilized. The algae were grown in Molisch's culture 

 medium and the fungi in Raulin's liquid. For each kind of plant the only source of 

 nitrogen was to be found in the compound under investigation. 



Flowering plants, algae, and fungi can take the nitrogen necessary for their growth 

 from salts containing amin compounds. This appears to take place without trans- 

 formation into nitric or ammoniacal nitrogen. Methylamin is an excellent source of 

 nitrogen, but benzylamin is not, and phenylamin is poisonous. The algae seem some- 

 what less subject to injury by phenylamin than flowering plants. Ammonia com- 

 pounds, pyridin bases, and alkaloids are not directly assimilable, but they may 

 become available in the presence of some form of assimilable nitrogen. The same 

 rule applies for the alkaloids as for the amins, the less complex the molecule the 

 more assimilable they are. 



The instability of amid compounds limited their use to algae and fungi. As with 

 the amins, the amids of the fatty series are directly assimilable by plants, but those 

 of the aromatic series are not adapted to plant growth. The investigations showed 

 that asparagin and urea caused better growth than the form of nitrogen existing in 

 Raulin's fluid. Leucin and tyrosin under conditions described above are assimilable 

 by each class of plants studied. The nitriles are only slightly assimilable when 

 used alone, but when usedMn connection with other forms of nitrogen are taken up 

 to some extent by the plants. 



Compounds of the aromatic series are either not assimilable at all or are poisonous 

 to plants. Comparing the assimilability of the amin, amid, and nitrile compounds, 

 it is stated that for compounds of equal molecular complexity the amins are the most 

 assimilable, followed by the amids and nitriles. Hydroxalamin acted as slightly 

 toxic to all plants tested. 



