44 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Study of Chitin.* — D. H. Wester finds that chitin, as found in 

 animals and plants, is identical : it never gives albumen-reaction, and is 

 not coloured by iodine solution. Chitin is not digestible, and as much 

 of the estimated nitrogenous substance of fungi is chitin, the nutritive 

 value of fungi is seriously called in question. 



Wester's work was largely taken up with the localisation of chitin 

 in animals and plants. It is of frequent occurrence in fungi : Miner 

 and Phycomyces nitens have considerable quantities in their cell-walls, 

 but no cellulose ; the spores of Peziza aurantia show more of it, while in 

 the fungus itself it is abundant. Results were very varied in lichens, 

 according to the species examined ; age also was a factor in the case : 

 the author considers that the symbiotic conditions probably affect the 

 quantity of chitins. Complications were also caused by the presence 

 of licheuin. None of the substance was detected in Cyanophyeere or 

 in Myxomycetes, except in the spores of Plasmodiophora Brassicee. 

 Bacteria were free from chitins, as were all the other plants examined. 



Structure and Development. 



"Vegetative. 

 Wood Structure in Pinese.t — I. W. Bailey has investigated the 

 structure of wood in the Pinere, and the following appear to be 

 the most notable features. In Picea the wood-parenchyma occurs in the 

 outer parts of the summer wood, and in a few instances is strongly 

 developed. It is only poorly developed in Larix and Pseudotsuga. In 

 all three genera septate tracheids occur which clearly show the transition 

 from wood-parenchyma. In Pinus similar tracheids occur, but wood- 

 parenchyma is rare. There are spiral thickenings of the tracheids in 

 the spring and summer wood of Picea and Pseudotsuga, and they are 

 also found in Pinus. Such thickenings also occur in the marginal 

 tracheids, and those interpersed in the medullary rays of Picea, Larix, 

 and Pseudotsuga. Pinus appears to be distinct from other modern 

 Pineae, but the nut and foxtail pines have certain details in the structure 

 of their wood which resemble the structure of the wood in Picea, Larix, 

 and Pseudotsuga. The author concludes "that the identification of 

 woods and fossils of Picea, Larix, and Pseudotsuga is an extremely 

 difficult undertaking." 



Wild and Cultivated Dioscorea in Tropical Africa.^ — A. Chevalier 

 contributes a note upon the yams of tropical West Africa. In the 

 virgin forests, near the sources of the Niger and Chari, the author has 

 observed large quantities of a wild plant which he regards as an 

 undoubted spontaneous species of Dioscorea prehensilis. In the neigh- 

 bourhood of Baoute and the Ivory. Coast thirty races of yams are 

 cultivated for food and medicinal purposes, and these are all included 

 under the three species D. latifolia, D. (data, and D. prehensilis. These 

 races are distinguishable by the gradation and frequency of the spines 

 on the stem, the ramification and length of the brauches, and the 

 colour, size, and form of the leaves. The most distinguishing charac- 



* Arch. Pharm., ccxlvii. (1909) pp. 282-307. See also Bot. Zeit., lxvii. (1909) 

 pp. 293-4. t Bot. Gaz., xlviii. (1909) pp. 47-55 (1 pi.). 



X Comptes Rendus, cxlix. (1909) pp. 610-12. 



