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‘Bot, VIII. 23 13728, plate 13. “35 
1897 | CURRENT LITERATURE 59 
directly contradictory to that offered by Leitgeb and afforded by Stahl's 
Cobaltprobe* The cobalt chloride test for the condition of stomata the 
author regards as not affording such absolute evidence of stomatic condi- 
tions as his own microscopic observation, cuticular transpiration confounding 
the results obtained by the former means. Finally it is stated that all obser- 
vations made by the author point toward a return to the conclusions of 
Schwendener, that the guard cells as independent organs effect the opening 
and closure of stomata by means of the variations in their osmotic pressure, 
induced in turn by variation in the activity of assimilation working under the 
influence of light; and hence stomata are controlled by assimilation, being 
open in light and closed in darkness, and influencing transpiration through 
physical necessity. Against the conclusion of Leitgeb, that these structures 
are organs of transpiration rather than assimilation, it is urged that change 
in illumination is shown to be a much more powerful factor in effecting the 
stomatic movements than changes in water supply; that evidence of the 
closure of stomata before apparent wilting is insufficient to prove the case ; 
that stomata closed in darkness cannot be opened by increase of moisture in 
the atmosphere nor by artificially induced root pressure; and, finally, that 
stomata are, more than anything else, open when assimilation is most active 
and closed when darkness diminishes this activity and hence induces flaccidity 
of chlorophyll-containing guard cells.—J. G. C. 
M. E. D’HuBert has written an interesting paper> upon the embryo sac 
of fleshy plants. After devoting considerable space to an historical résumé 
of the physiological and morphological problems of reproduction, he gives a 
detailed account of the ovules of the Cactacez, Mesembrianthemacez, and 
Crassulacez. In the Cactacee the funiculus contains starch, bnt none is 
found in the nucleus. Starch appears in the embryo sac at the time of the 
first division of the nucleus, and increases in quantity as the sac develops. 
Just before fertilization the synergids, oosphere, and polar nuclei are richly 
supplied with starch, ic the antipodals have lost much of their starch 
re polar naciel, which are very ate in 1 fusing. “When the pollen tube 
_ reaches the sac, the nucleus of one synergid advances to meet the nucleus 
of the tube, while oF selec the other synergid moves: toward the nucleus 
of the oosphere. The polar nuclei now fuse, and the resulting nucleus 
_ tEinige Versuche iiber — Assil a. Dx cat inaguie, ~ ae 
1894. 
Siecheveties 3 sur le Sac embryonnair : des Plantes een ‘Ann. Sci. Na a 
