ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 205 



Chemical Changes. 



Oxidising Enzymes.* — C. E. Newton suggests the use of suitable 

 enzymes, procured from other plants, to aid and intensify the action of 

 the enzyme, thease, already existing in the tea-leaf, which is the 

 principal factor in the fermentation of the leaf. The author states 

 that considerable improvement in quality has taken place in those cases 

 in which he was able to try the plan ; and believes that if successful 

 it will probably have greater effects on the tobacco industry than on 

 that of tea. 



Proteolytic Enzyme of Nepenthes.f — Prof. Vines criticises the 

 results of experiments in vitro by the late Georges Clautriau who con- 

 cluded that the proteolytic enzyme present in the pitchers of Nepenthes 

 was a pepsin, that is, an enzyme acting on the higher proteids in an 

 acid medium giving rise to peptoues, but incapable of decomposing 

 proteids into non-proteid substances, such as leucin and tyrosin. Clau- 

 triau had also adversely criticised Vines's statement that the enzyme 

 is not peptic, but tryptic in action. In his present paper the author 

 adduces the tryptophan reaction in support of his view. It has been 

 shown that chlorine-water when added to the liquid resulting from a 

 pancreatic (tryptic) digestion, gives after acidification, a colour varying, 

 according to concentration, from pink to violet. This coloration is due 

 to the presence of a substance (tryptophan) which together with leucin, 

 tyrosin, and other bodies, is a product of tryptic, as distinguished from 

 peptic, proteolysis. Vines obtains this colour reaction with the liquids 

 resulting from the digestion in pitchers of Nepenthes, and also from the 

 digestion of fibrin by pine-apple juice and papain. He therefore con- 

 cludes that the three enzymes, nepenthin, bromelin, and papain, have 

 essentially the same proteolytic action — a tryptic one, though they differ 

 as regards the media in which they act. Nepenthin, like pepsin, acts 

 only in acid liquids, bromelin and papain are most active in neutral 

 liquids, while the animal ferment trypsin is most active in alkaline 

 liquids. These results strengthen the suggestion that all known proteo- 

 lytic plant enzymes are tryptic in action. 



Starch-formation in Hydrodictyon utriculatum.J — H. G. Timber- 

 lake investigates the nature of the relation of the pyrenoid to the 

 formation of starch. Hydrodictyon contains no differentiated chromato- 

 phore, both pyrenoids and nuclei are scattered throughout the proto- 

 plasmic layer, often in immediate juxtaposition. The whole process of 

 starch-formation can be traced from structural changes occurring in the 

 body of the pyrenoid, the first indication of which is its differentiation 

 into two portions, one of which is transformed into a starch-grain, while 

 the other remains unchanged. The starch-grain when formed is sepa- 

 rated from the pyrenoid and appears to lie in a vesicle or vacuole in the 

 cytoplasm. When starch-formation is going on very rapidly, the grains, 

 as they are formed, are continually crowded outward by the later- 

 formed grains, so that finally they are densely packed through nearly 

 the whole protoplast. 



* Indian Gardening and Planting, Nov. 28, 1901. 

 t Ann. Bat, xv. (1901) pp. 564-73. J Tom. cit, pp. 619-35 (1 pi.). 



