﻿66 BOTANICAL GAZETTE [January 



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following results : Papain is active in both acid and alkaline media, forming 

 caseoses and casein peptones which closely resemble these bodies as they are 

 produced in gastric digestion. Thus this enzyme is like pepsin as to the 

 products of its action, but unlike it in that pepsin cannot act in an alkaline [ 



medium. Trypsin, as is well known, develops its action in an alkaline 

 medium as well as in an acid one, but its products are quite different from 

 those of pepsin, being mainly leucin, tyrosin, and tryptophan, none of which 

 were found among the products of papain digestion. Mendel concludes, 

 therefore, that papain must be regarded as belonging to a class quite distinct 



from that of either pepsin or trypsin. — Burton E. Livingston. 



Palladin''* has added to his former researches concerning the genera- 

 tion of chlorophyll in etiolated leaves. He had already shown that such 

 leaves, when cut and exposed to sunlight, fail to become green unless they 

 contain carbohydrate material or are supplied with it from a solution into 

 which they dip.^^ Moreover, not only can solutions of saccharose and glucose 

 bring about this effect, but other carbohydrates are also available, e, g.y raffi- 

 nose, fructose, maltose, and even glycerin.^^ In the present study he has been 

 able to show that the formation of chlorophyll in such leaves depends upon the 

 concentration of the solution, which may be either too weak or too strong to 

 produce the response. The optimum greening is in a medium concentration. 

 That strong solutions of saccharose can inhibit greening is explained by the 

 fact that they greatly retard oxidation ; the process of chlorophyll formation 



is known to b, at least in part, one of oxidation. — Burton E. Livingston. 



In the fourth of his studies on the genus Selaginella, Harvey-Gibson =*7 

 discusses the anatomy and development of the root. He concludes that the 

 so-called rhizophores which are characteristic of certain species of Selagi- 

 nella do not possess the morphological value of caulomes, but are merely the 

 aerial portions of roots. He points out their close relation to branches, a 

 correlation which, by the way, presents a striking parallel to the condition \ 



found in Equisetum and the other Lycopsida. The author suggests that, in 



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those cases where a leafy branch grows out from the situs of a rhizophore, 

 there is really present a branch-root combination in which the root has been 

 suppressed. The internal structure of the typical root and the rhizophore is 

 the same, both being monarchous and possessing a well-marked endodermis. 

 The xylem of the root is generally perixylic, but in the rhizophoric portions 



'^Palladin, W., Einfluss der concentration der Losungen auf die Chlorophyll- 

 bildung in etiolirten Blattern. Ber. Deutsch. Bot. Gesell. 20 : 224-228. 1902. 



»s Palladin, W., Ergriinen und Wachsthum der Etiolirten Blatter. Ber, Deutsch. 

 Bot. Gesell. 9:429. 1891. 



26 pALLADiN,\V,, Recherches sur la formation de la chlorophylle dans des plantes. 

 Rev. Gen. Bot. 9:385. 1891. 



»7 Harvey-Gibson, R. J., Contributions towards a knowledge of the anatomy of 

 the genus Selaginella. Ann. Botany 16: 449-466. pis, 20-21. 1902. 



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