158 PHYSIOLOGY OF NUTRITION 



shown that asparagin arises during synthetic processes. Borodin' had ahready 

 observed that no asparagin is formed in the absence of oxygen. The researches 

 of Palladin have recently been repeated and substantiated by Godlewski,^ and 

 Butkevich' also obtained similar results. Aspergillus niger decomposes 

 peptones to ammonia in the presence of oxygen, but only to amino acids in the 

 absence of this element. It still remains uncertain in what way asparagin is 

 formed from the primary products of protein cleavage, but it seems possible 

 that here, also, an enzymatic process is involved. 



The formation of the various nitrogenous cleavage products of proteins is 

 also dependent upon the chemical nature of the nutrient medium in which the 

 organism is grown. Butkevich^ showed that different moulds do not produce 

 the same cleavage products when grown in peptone solution. Aspergillus 

 niger produces ammonia mainly, while Penicillium glaucum forms tyrosin and 

 leucin for the most part. This difference is correlated with the acid or alkahne 

 reaction of the substratum. Aspergillus forms a considerable amount of oxaUc 

 acid and this renders the nutrient solution acid. Penicillium produces no oxalic 

 acid and the solution in which it is growing soon becomes alkaline, as a result 

 of ammonia formation. If, however, Aspergillus is cultivated with an excess 

 of calcium carbonate in the medium, then it forms considerable amounts of 

 tyrosin and leucin, while Penicillium produces ammonia in considerable amount 

 when the nutrient solution is rendered acid by addition of phosphoric acid. 



Not only the simple or reserve proteins but also the so-caUed formative 

 proteins, are broken down in the plant. When seeds germinate in darkness 

 adenin, guanin, xanthin and hypoxanthin are produced, as cleavage products 

 of nucleic acid. The studies of Karapetovaand Sobashnikova,^ who employed 

 seedlings of rye and barley grown with inadequate nutrition, show that the 

 proteins found to be indigestible in gastric juice are not as easily broken down 

 in the plant as are the ones that are digestible in gastric juice. In the early 

 stages of development the amount of indigestible proteins actually increases, 

 while the total amount of protein decreases. Decomposition of the indigestible 

 proteins occurs later. Zaliesskii^ has also pointed out that nucleo-proteins are to 

 be considered as formative (non-reserve) materials, on account of their relative 

 stability as revealed by their behavior when the organism is in a starved condi- 

 tion. It may be supposed that those substances that are first decomposed dur- 

 ing starvation are nutrient materials, while those remaining unchanged are 

 constituents of the protoplasm. Pronounced decomposition of the nucleo- 

 proteins is to be observed only in dead plants that still possess active enzymes. 



> Borodin, I. P., On the conditions for the accumulation of leucin in plants. [Russian.] Trav. Soc. 

 Imp. Nat. St.-P6tersbourg 16 (Protocole): 69-73. 1885. 



2 Godlewski, E., Nouvelle contribution h. I'itude de la respiration intramoUculaire des plantes. [Title 

 in Polish, German and French.] Bull. Int. Acad. Sci. Cracovie (Math.-nat. CI.) (Anz. Akad. Wiss. 

 Krakau.) 1904: 115-158. 1904. 



» Butkewltsch, Wl., Umwandlung der Eiweissstoffe duroh die niederen Pilze im Zusammenhange mit 

 einigen Bedingungen ihrer Entwickelung. Jahrb. wiss. Bot. 38: 147-240. 1903. 



• Butkevich, 1903. [See note 3, this page.] 



• KarapStoff, H., and SabachnikofE, M., Sur le diScomposition des matiSres protfiiques dans les plantes. 

 Rev. gin. bot. 14: 483-486. 1902. 



• Zaleski, W., Ueber die RoUe der Nucleoproteide in den Pflanzen. Ber. Deutsch. Bot. Ges. 29 : 146- 

 ISS. 1911 



