BOTANY. 229 



that when the fungus continued to grow in a second medium and to assimilate the 

 alkaloids it was due to a certain extent al least to the presence of ammoniacal nitro- 

 gen in the mycelium enabling the fungus to utilize the nitrogen present in the 

 alkaloid. 



From this the author concludes that alkaloids secreted by plants are not to be con- 

 sidered as reserve substances but only as by-products of the plant, and are utilized 

 only under special conditions. 



Notes on assimilation by chlorophyll, 0. Bernard (Bot. Centbl. Beihefte, 

 16 (1904), No. 1, pp. 36-52, figs. .'; abs. in lint. Centbl, 95 (1904), No. 21, pp. 563, 

 564). — Following the methods of Friedel and Macchiati (E. S. R., 14, p. 1047), the 

 author has endeavored to ascertain the power of chlorophyll to carry on photosyn- 

 thesis w hen removed from the living plant. Fjxperhnents are reported with spinach 

 and various aquatic plants, the tests being made by improved methods, but in every 

 case negative results were obtained. The author concludes that the hypothesis of 

 enzymic action by chlorophyll, as far as his experiments go, is not demonstrated. 



The effect of temperature on carbon-dioxid assimilation, Gabrielle L. C. 

 Matthaki i Proc. Roy. Soc. [London], 72 (1903), No. 483, pp. 355, 356). — A summary 

 is given of investigations made witli cherry-laurel leaves to determine the carbon- 

 dioxid assimilation as affected by temperatures. 



These leaves were subjected to temperatures ranging from —6 to 45° C. At each 

 temperature illumination at different intensities was required in order to make cer- 

 tain that the amount of assimilation was not limited by insufficient lighting. When 

 a leaf is exposed to light of high intensity the excess of radiation raises the tempera- 

 ture of the leaf above that indicated by an adjacent thermometer, and under some 

 of the conditions of the experiments this excess amounted to as much as 10° C. 



The various precautions adopted to eliminate error in experiments are described, 

 and after taking all factors into consideration it was found that the respiration 

 becomes determinable at —6° C. and then rises rapidly with the higher temperatures 

 up to 38° C. At temperatures above this point the leaf is not capable of maintaining 

 its high rate of assimilation for any length of time, so that the values obtained for 

 successive hourly estimation of the same leaf form a rapidly declining series. The 

 higher the temperature the shorter the duration of the period of maximum assimila- 

 tion and it becomes impossible to obtain the maximum values at temperatures close 

 to 45° C, which was the fatal temperature for the leaves experimented with. The 

 optimum temperature for assimilation was 38° C. 



Some results of cross pollination, Leclerc du Sablox (Compt. Rend. Acad. 

 Sri. Paris, 137 (1903), No. 26, pp. 1298, 1299; abs. in Bot. Centbl., 95 (1904), No. 8, p. 

 180). — The effect on the carbohydrates in the pericarp of a number of cucurbit spe- 

 cies in which the pollen was transferred from one species to another is shown. The 

 author transferred the pollen from melons to melons, from melons to cucumbers, 

 from cucumbers to melons, and from cucumbers to cucumbers. 



The fruits produced were analyzed at maturity, and while there was no visible 

 effect due to the cross pollination, yet the melon which resulted from the stimulus 

 of the cucumber pollen did not possess the ordinary sweet taste of melons. An 

 analysis of the pericarp showed that the influence of the cucumber pollen had 

 diminished the sugar content from 24.3 per cent to 5.8 per cent. The contrary cross 

 of melon pollen on cucumber did not result in any increase of sugar in the cucumber. 

 Cross pollination of different varieties of squash are described, in which there was 

 no modification of a morphological character, but a decided diminution of the carbo- 

 hydrates. 



