488 SUMMARY OF CURRENT RESEARCHES RELATING TO 



theory of doubly refractive micella), and the theory of crystalline 

 structure. Herr A. Zimnicrinann contributes a paper towards the 

 solution of this question. He believes that the anisotropy is caused 

 chiefly by the arrangement of the micella; constituting the substance. 

 It is, however, not improbable — although it cannot be proved by 

 direct observation — that the micella; possess in themselves a power 

 of double refraction. The theory that crystalline structure of organic 

 substances which produces anisotropy is brought about by tension is 

 not impossible, and is supported by certain facts; but it is not 

 probable that these tensions still remain in the vegetable membrane 

 at a later period. 



Chemical Phenomena of the Respiration of Plants.* — Dr. T. 

 L. Phipson in connection wdtli the general idea that the exposure of 

 the green parts of plants to light is sufficient to cause them to breathe, 

 remarks that temi)erature is quite as important an agent. For examide, 

 plants were exposed to light on two days of nearly equal pliotomctric 

 intensity of daylight ; but when the temperature was respectively 

 38^ F. and 70" F., in the first case the evolution of gas was nil, whilst 

 in the second it was abundant. On another occasion a plant at 45° F. 

 in bright sunlight gave no gas, whereas, after an hour at 59° F. in 

 much less powerful light, gas was evolved. 



The plants employed in these observations were unicellular alga; ; 

 they have no stomata, it is therefore inferred that these organs are 

 not indispensable for the respiration of plants. A temperature of 

 from GO ° F. to 90^ F., and exposure to sunlight appear to be the 

 most favourable conditions for the respiration of these plants. Other 

 observations and experiments tend to show that circulation is closely 

 connected with resi)iratiou, and, like it, is equally dependent on tem- 

 perature as well as light. It is stated that the oxygen evolved from 

 tlie organisms in stagnant water comes from zoospores, and not from 

 infusoria, as is sometimes supposed. It is inferred tliat the respira- 

 tion of plants is independent of chlorophyll, but that chlorophyll is 

 formed by the process of respiration, inasmuch as the brown or 

 yellowish Protococcus plmialis emits oxygen, and algas accidentally 

 bleached by adding a minute quantity of sodium hydroxide to the 

 water in which they were being cultivated, after washing and again 

 exposing to light, gave off oxygen after four hours, and the next day 

 developed green patches. The author's experiments negative the 

 idea that for the cultivation of plants, carbonic anhydride may be 

 replaced by organic acids. 



Eespiration of Leaves in Darkness.f — The researches on this 

 subject by MM. G. Bonnier and L. Mangin are now published more 

 in detail, with a description of the experiments themselves and of the 

 apparatus employed, together with a number of tables. The relation 

 between the volume of carbon dioxide given off and that of oxygen 



* Chcm. News, 1. (1884) p. 288. Sec Journ. Chcm. Soc— Abstr., xlviii. 

 (1885) pp. 420-1. 



t Aim. Sci. Nut.— Lot., xix. (1884) pp. 217-55. Cf. this Journal, iv. (1884) 



p. 5r»i. 



