■ 



/ 



236 . . BOTANICAL GAZETTE [September 



ical principles underlying' solution of these gases and the methods best 

 adapted to their determination in natural waters are quite fully treated. 

 Ordinarily both carbon dioxid and oxygen are necessary for the life of the 

 micro-organisms in natural waters. Consideration of the relative amounts of 

 these gases is shown to be of great value in explaining certain problems of 

 vertical and seasonal distribution. What seems to be a causal relation is 

 pointed out between the great carbon dioxid content of ground waters and 



r 



their peculiar tendency to support diatom growth. Interesting curves and 

 tables accompany the paper. — B. E. Livingston. 



John Cutler Torkey,^^ in studying the *' Cytological changes accom- 

 panying the secretion of diastase," concludes that among the grasses ''diastase 

 of secretion" arises in the nucleus of the epidermal cells of the scutellum ; 

 that zymogenesis begins in the nuclei before the advent of the resting period ; 

 that at some time during the first and third days of germination the diastase- 

 secreting cells swell to three or four times their original size ; that during the 

 first and third days there are " waves '* of secretion, so that this process may be 

 described as intermittent, but from that time on, until final exhaustion of the 

 cells, the secretion is more continuous ; that the secreting cells begin to 

 degenerate about the tenth day; that it is highly probable that the chromatin 

 takes an active part in the zymogenesis ; that the nucleus is in this case very 

 clearly the metabolic center of the cell ; and that there is a marked differ- 

 ence in secretory processes in plants and animals, — J. M. C. 



L, Cockayne'^ continues the account of his studies of the seedlings of 

 New Zealand and Chatham island plants. He finds that many species com- 

 mon to New Zealand and Chatham islands are similar in their young stages, 

 but become different in their adult forms, the New Zealand forms becoming 

 strongly xerophilous in structure, while those from Chatham island retain 

 their juvenile characters, A number of New Zealand species pass through 

 three distinct stages in their individual development: first the juvenile form, 

 then this gives place to an extremely xerophilous form, and finally this is 

 replaced by a form which resembles the first. Similar forms from Chatham 

 island do not pass through the xerophilous stage, and the New Zealand 

 plants when grftwn under favorable conditions of moisture omit this stage 

 also, resembling the juvenile form throughout. The author considers the 

 bearing of these facts on the relationships and history of the flora of these ^ 

 two regions. — W. B. McCallum. 



Valuable determinations of the constituents of the fruit of the cocoa- 

 nut {Cocos 7iticzfera) are given by J. E. Kirkwood and W. J. Gies.^* The milk 

 '♦Bull. Terr. Bot. Club 29: 421-435. 1902. 



'SAn inquiry into the seedling forms of New Zealand phanerogams and their 

 development. Trans. New Zealand Inst. 33: 265-299. pis. 10-12. 1900. 



"^Chemical studies of the cocoanut with some notes on the changes during 

 germination. Contrib. N. Y. Bot. Garden no. 26. Bull. Torn Bot. Club 20 : 32 1-359- 

 //. iQ, figs, i~6. 1902, 



