KozLOWsKi : Primary Synthesis of Proteids 41 



the amides on the one hand, and between the latter and proteids 



on the other ? 



; The first can be answered with greater certainty owing to the 

 investigation of the past few years. As to the second — it can be 

 answ^ered only hypothctically ; but as every experimental science 

 IS in the same degree dependent upon facts, and upon scientific 

 ideas, and as observation or experiment is always guided by scien- 

 tific hypothesis, we ought not to throw aside suppositions which 

 can be induced from facts and arc not at variance with the general 



spirit of "scientific thought. 



As to organs In which proteids are produced a supposition was 

 given as long ago as 1862 by Sachs,* who considered the leaves 

 as active in this process, Hansteln was led to the same results by 

 his experiments in girdling shoots, and Pfcffer showed that the de- 

 velopment of blossoms and buds is dependent upon the presence 

 of leaves and the supply of the substance w^hich circulates in the 



sieve tubes. 



The same conclusion must be drawn from the above quoted 



r 



investigations concerning the distribution of nitrogen compounds 

 in plants. The general result is that the organic nitrogen com- 

 pounds are accumulated in leaves until the latter reach their full 

 development, then they decrease in order to be transferred into 

 fruits and finally disappear from the stem and the leaves while they 

 are still increasing in the fruits even if the plant is not supplied 



with nitrogen from outside. 



But quite decisive are the investigations of A. F. W. Schimper,t 

 who showed by means of the reaction with diphenylamin that the 

 nitrates pass as such through the fibro-vascular bundle of leaves 

 and disappear in the chlorophylic cells of the mesophyl while 

 large amounts of calcium oxalate is produced, the calcium being 

 combined with the nitric acid as calcium nitrate entering the plant 

 through the roots. This disappearance occurs only in light, while 

 in darkness or in leaves free from chlorophyl the nitrates are ac- 

 cumulated in large amount. The experiments of Schimper and 

 many others make it probable that in the same way sulphites and 



* Botanische Zcitung, and the articles scattered through the 45 vols, of Flora ( 1862 

 seq.) where the cribrose vessels are indicated as the place of formation of proteids. 

 f Bot. Zeitung, 188S, N. N. 5-10. 



