ON AN IMPORTANT FUNCTION OF LEAVFS. 



243 



But I thought that a decrease of proteids should take place 

 in the leaves even in one night because we know that during 

 every night a large portion of the carbohydrates in the leaves is 

 transported into the other parts of the plants. This decrease of 

 the protecting carbohydrates must naturally lead to an attack 

 upon the reserve proteids formed in the leaves during the day, 

 and, as the resulting amido-compounds Avould just as easily be 

 transportable as sugar, a decrease of the proteids of the leaves 

 during the night should be easy to prove. Thus far only one 

 experiment in this direction has been made with the leaves of 

 Vitis iiinifera, by Saposnikozv^^^' who infers as follows : — 



" Aus der dritten Reihe von Versuchen mit, an den 

 Pflanzen belassenen Blattern ergab sich, dass im Dunkeln das 

 Eiweiss ebenso wie die Kohlenhydrate, wenn auch im gerin- 

 gerem Maase, aus den Blattern auswandert. Von einigen 

 Blattern, wurde je eine Halfte um 7 Uhr abends abgeschnitten, 

 die andere verdunkelt an der Pflanze gelassen and um 8 Uhr 

 morgens abgeschsuitten ; wiihrend dieser 13 Stunden vermindertc 

 sich der Eiweissgehalt pro q. m. um 0.281 gram ; in einem 

 zweiten Versuche wurden die an der Pflanze balasenen Blatt- 

 hiilften fiinf Tage lang Verdunkelt, die Verminderung des Eiweiss- 

 gehaltes pro q. m. betrug 1.267 gi'am wiihrend der Gehalt an 

 Kohlehydraten um 3.681 gram abnahm ; der gleichzeitig bestimm- 

 te Nicht-Eiweiss-Stikstoff nahm nur ganz unbedeutend zu." 



But this one experiment is certainly not sufficient to show 

 that this law holds good also for a great number of plants. I 

 therefore carried on some more experiments with plants from 

 different families, determining in the morning and in the evening 

 not only the total nitrogen and albuminoid nitrogen, but also the 

 aspragine nitrogen and the starch. The results are as follows : — 



# 



I. Experiments with Leguminous Plants, 



A. Wistaria bracJiybotrys (Fuji). 



400 leaves. 



Dry weight. 



20.089 grams 

 17.094 ,, 



(I) Cent. Bl. cl. Agr. Chem, 1896 p. 107. 



