472 SUMMARY OF CURRENT RESEARCHES RELATING TO 



consider that there is sufficient evidence to prove that carbon monoxide 

 may not be an intermediate product in the assimilation of C0 2 . " It is 

 possible that it takes part in reaction in the nascent state, or perhaps 

 that the simultaneous formation of other substances may be necessary 

 in order that assimilation may take place." 



Absorption of Water by Seeds.* — W. R. G-. Atkins has experimented 

 with seeds of Phaseolus vulgaris and Lathyrus odoratus, with the follow- 

 ing results. Bean seeds, living or dead, take up the same amount of 

 water in initial stages, and the final weight reached is independent of the 

 presence of KN0 3 . Distilled water is not absorbed more rapidly than 

 salt solution. Seeds placed in solution of KN0 3 and then in water, lose 

 weight, but the final weight is what it would have been if they had been 

 placed direct in pure water. N/0 H 2 S0 4 solution, N/10 iodine and 

 N/10 sodium chloride, are practically unchanged in concentration by 

 having seeds soaked in them, but iodine is decolorised. Thus, seeds 

 have no semipermeable membrane till germination begins and cell-pro- 

 toplasm becomes active. There is no difference between the absorption 

 of dead and living seeds until the commencement of germination, since 

 capillarity and imbibition are the forces concerned before germination, 

 but afterwards osmosis comes into action. 



Respiration of the Aerial Parts of Vascular Plants.j— G. Nicolas 

 contributes a note upon some experiments which he has performed upon 

 Pirns communis, Nerium Oleander, etc., with the purpose of investigating 

 the cause of the greater respiratory energy of leaves when compared 

 with that of the stem, petiole, etc. When the leaves were covered with 

 vaseline the respiratory energy was decreased and the ratios U0 2 /0 

 and 1/N were increased. Thus the author concludes that the greater 

 respiratory energy of the leaves is due to the greater facility for the 

 penetration and circulation of gas, which they present. 



Irritability. 



Germination of Phacelia.^ — E. Heinricher has investigated the 

 results produced by change of light during the germination of P. tana- 

 cetifolia, and finds that the rays of the first half of the spectrum and 

 also ordinary diffused light are unfavourable to germination, while dark- 

 ness and the rays of the second half of the spectrum are advantageous. 

 Seeds which have been sown immediately after harvest are especially 

 sensitive to the retarding influence of light. If seeds which are to be 

 germinated in darkness are previously kept dry for a short time, it is 

 found that the percentage of good germinations is largely increased, 

 but seeds sown in the light are unaffected by this treatment. In its 

 response to the influence of light Phacelia greatly resembles Veronica 

 peregrina. The reason of this influence must be sought in the photo- 

 chemical action brought about in the food-reserve. It would appear 

 that the effect of the fat-splitting lipase is favoured by the formation of 

 acid that takes place in darkness, while light prevents this process to a 

 greater or lesser extent in proportion to its intensity. 



* Sci. Proc. Roy. Dublin Soc, xii. (1909) pp. 35-46. 

 t Comptes Rendus, cxlviii. (1909) pp. 1333-36. 

 X Bot. Zeit., lxvii. (1909) pp. 45-66. 



