520 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Forest Destruction in the United States.*- — G. Pinchot supplies 

 notes on forest-destruction, its effects, and the methods of regeneration. 

 The notes are illustrated by an excellent series of photographic repro- 

 ductions. 



Poisonous Action and Histology of Stem of Derris uliginosa.f — 

 F. B. Power has made a detailed analysis of the stem of this fish-poison. 

 No alkaloid was found in the bark, but a considerable amount of tannin 

 and red colouring matter. A resin was extracted with petroleum, and 

 the toxic effect was found to be due to some constituent of that portion 

 of the resin which is soluble in chloroform and not to the tannin. 

 The portion of the resin insoluble in the chloroform had no toxic 

 effect. 



P. E. F. Perredes X gives a detailed description of the minute anatomy 

 of the stem of the plant. 



Mercerisation of Cotton Fabrics. § — L. Buscalioni describes the 

 various improvements made upon the process discovered by Mercer in 

 1845, by which cotton cloth treated with caustic soda becomes semi- 

 transparent and stronger, and absorbs dyes more readily. He then 

 enters into a minute description of the microscopical structure of various 

 cotton fibres, their optical and chemical characters, the effect of mer- 

 cerisation. The opacity of raw cotton is partly due to the air-cavity 

 in the fibre, and the transparency of mercerised cotton is due to the 

 partial expulsion of the air under the stretching and compression em- 

 ployed in the modern improved processes. A long list of papers bearing 

 on the subject is appended. 



CRYPTOGAMS. 



Pteridophyta. 



Root-Development in Azolla.|] — R. G-. Leavitt notes some points of 

 difference between results obtained by himself in the development of the 

 root-sheath and cap in Azolla filiculoides and A. caroliniana, and the 

 description given by Strasburger of the process in the former species. 

 He also describes in detail the development of the root-hairs, the initial 

 cells of which arise within a belt of actively dividing cells, immediately 

 beneath the inner root-cap, not far from the apex. The cell does not 

 elongate much in a direction parallel with the length of the root. As 

 the hairs lengthen they lie at first appressed to the root distending the 

 inner cap. The whole root-cap is finally thrown off through the growth 

 of the lower hairs. Owing to the elongation and transverse division of 

 the cells produced simultaneously with the hair initial, the hairs in each 

 longitudinal row become separated by 2-8 cells. 



The superficial layer of the root-trunk in these two species of Azolla 

 comprised, apart from the apical cell, four regions, viz. (1) a region of 

 embryonic tissue in which the divisions are equating divisions ; (2) a 



* Rep. Smithsonian Inst, for 1901 (1902) pp. 401-4 (4 pis.). 



t Wellcome Chem. Research Laboratories, No. 34 (1903) pp. 1-25. 



t Op. cit, No. 35, 1903, pp. 1-10 (9 pis.). 



§ Atti d. Istit. Bot. Univ. Pavia. vii. (19021 pp. 195-227 (2 pis.). 



H Bot. Gazette, xxxiv. (1902) pp. 414-9 (1 pi.). 



