BOTANY. 109 



« 



Potassium — microchemical detection, K. I\I. Chamot (Jniir. A/ij)/. }[irr(>s., S 

 [lUdO], .V'/. /.', pjK /()77-/'>M, Ji(/K. r>). — Metliods of foriiuitioii aii<l dotuftioii of cry.s- 

 tals of potassium salts in various materials. 



Chemistry in its relation to agriculture, F. B. (Jutiiiuio (.I'/r. (i<tz. Xcir Santh 

 Wnlrx, IJ (1901), X<>. 7, />/,. 1 1.h/->'0, Ji'jx. J).—X jrciicral rcvii-w of the suliject with 

 special referoiu-t' to the progress of agricultural chemistry in Australia. 



BOTANY. 



Critical points in the relation of lig-ht to plants, D. T. MAcDoruAi, {.\hs. in 

 ,Srinii-<\, II. SIT., J.) [lUOl), y<>. .)J0, p. ..'5J). — The influence of light upon plants is 

 summarized 1)y the author as follows: " Light exercises a direct ciiemical effect upon 

 the substances of which j)rotoplasm is composed. It stinuilates protoplasm to the 

 formation of chlorophyll, although its action is not necessary to the proct-ss, and its 

 direct chemical effect disintegrates this substance. It constitutes a source of energy 

 w hich is absorbed by the chloroplasts. Absence of light constitutes a specific stimu- 

 lus, calling out the various reactions of etiolation. Light acts as a directive; or orient- 

 ing stimulus to which the plant responds by locomotory or bending movements. 

 Different portions of the spectrum are operative in producing these sei)arate effects." 

 The -author states that illumination is not necessary to the motility of protoplasm, 

 and conversely that the deprivation of light does not induce a condition of rigor, but 

 sets up various pathological phenomena, among which is the l)reaking down of 

 chlorophyll. Light does not exert a paratonic or retarding effect upon growth. Its 

 chemical action may hinder the acc-umulation of somatic material. The changed 

 development of plants in darkness is an adaptive response which has for its purpose 

 the elevation of the chlorophyll screen and reproductive bodies. 



On the development of etiolated plants when placed in sunlight, H. Rico .me 

 {Compt. Rend. Acad. Sri. Paru, 131 {1900), No. £6, pp. 1251-1253) .—TXw results of a 

 num])er of experiments in which etiolated plants were placed in the sunlight and 

 morphological changes noted are given. The effect of the change on the structure 

 of the stem and leaves and on the weight of the plants is shown. The stems of etio- 

 lated plants were consideral)ly longer than normal ones and the leaves were smaller 

 when the plant had l)ut iittle reserve material at its disposal. When plants having 

 a large amount of reserve material were deprived of light for a considerable time and 

 afterwards brought into the light, the effect of the etiolation was not as marked as 

 in the case of those plants having a limited amount of reserve material. Transpira- 

 tion was shown to play an important part in determining the effect of etiolation. It 

 was shown that etiolated plants brought out to the light suffered a great loss of 

 water, but this loss diminished as the dry weight of the plant increased. 



Contribution to the question of the synthesis of albumin by the higher 

 plants in the dark, K. Schkodkr {Izr. Momjv^ Sehk. Khoz. Fiisf., a [1900), Xn. 3, pp. 

 405-428). —The author experimented with squash, peas, potatoes, and dahlias. In 

 the case of the etiolated squash seedlings it was found that in the first two days 

 after the soaking of the seeds no decomposition of albumin took place, but after that 

 tlie albuminous substances began to decompose as usual. No synthesis of albumin 

 was observed. In the experiments with month-old etiolated pea seedlings, placed 

 in a T) per cent cane-sugar .soluti(m with other nutritive substances, no increa.se of 

 albuminous nitrogen was o])served, but there was a retarding of the decomposition 

 of the i)roteids. In the exi)eriments with potatoes germinated in sand cultures m 

 the dark an increase of the albuminous nitrogen was observed. In the absence of 

 j)ota.ssium nitrate there was either no increase or it was very sk>w. Dahlia tubers 

 germinated in pure (piartz sand and without nutritive sul)stances showed no increa.«e 

 of albuminous nitrogen. The above experiments, therefore, corroborate the state- 



