204 



SCIENCE. 



[N. S. Vol. XXIII. No. 580> 



of stomatal openings. No evidence is 

 found for the ' temporary opening ' of Pr. 

 Darwin. 



Absorption of Atmospheric Moisture iy 



Desert Shrubs: V. M. Spalding. 



The prolonged period during which Fou- 

 quieria splende')is and some other desert 

 shrubs remained in full leaf in the summer 

 and fall of 1905 suggested the probable 

 connection of this fact with the unusually 

 high relative humidity which prevailed 

 during that period. 



Experiments were carried out with 

 twelve different species of perennials to 

 ascertain whether they are capable of ab- 

 sorbing water vapor directly from the at- 

 mosphere. Leaves and other parts were 

 accurately weighed before and after ex- 

 posure to a saturated atmosphere. 



The leaves of Fouquieria do not absorb 

 water from the atmosphere, but the buds 

 and branches are capable of such absorp- 

 tion. In the case of Celtis pallida and a 

 number of other species there is no satis- 

 factory evidence of the absorption of water 

 vapor from the atmosphere by the living 

 parts of the plant before pathological 

 changes set in. Experiments with Covillea 

 tridentata indicate a positive, though lim- 

 ited capacity for leaf absorption. Other 

 plants vary in their deportment in this 

 respect. 



There is no evidence that the extremely 

 small amounts of water absorbed in this 

 way are utilized in the body of the plant, 

 but there is every reason to conclude that 

 high relative humidity proves to be a de- 

 cided advantage to various desert plants in 

 time of drouth by preventing excessive 

 transpiration of the leaves and thus pro- 

 longing the period of their physiological 

 activity. 



Correlation between Ovules and Matured 

 Seeds in Leguminous Fruits: J. A. 

 Harris. 



The paper is a study of the variability of 

 ovules and matured seeds in the fruits of 

 Cercis, Cassia, Wisteria and a garden bean.. 

 The series of constants is as yet too small to- 

 permit of any comparisons of the co- 

 efficients of regression of matured seeds on 

 ovules with those found in inheritance, but 

 the material promises some interesting re- 

 sults along this line. The regression would 

 seem to be an obstacle to the fixing of the 

 extremes of fluctuating variability by 

 natural selection. 



The Structure and Cytological Changes- 

 accompanying ■ Secretion in Nectar- 

 Glands of Vicia faba: Charles R.. 

 Stockard. 



The author finds that the nectar glands 

 on the stipules of Vicia faba contain layers 

 of cells whose contents have different chem- 

 ical reactions, which fact is indicated in 

 living material by their differences in 

 color. This probably points to a difference 

 in metabolic activity in the cells, since 

 those of definite layers have similar reac- 

 tions. The color response of the cells to 

 acids and bases is the typical litmus 

 change; acids causing the cell contents to 

 become red, bases changing it to blue. 



The nuclei are granular in structure, 

 often coarsely vacuolated with one or more 

 plasmosomes surrounded by vacuoles. 

 Their shape tends toward spherical, but 

 in old glands they become shrunken and 

 slightly irregular in form. The position 

 of the nucleus in the secreting cell varies' 

 greatly, btit is more often near the cell 

 center. It is never observed to give out 

 granular material directly to the cyto- 

 plasm, though evidence is strongly in favor 

 of the fact that it does transmit a sub- 

 stance to the cytoplasm which finally 

 forms, or causes to form, granules that 

 take in the older glands the nuclear stains. 

 In rare cases the nucleus loses its chro- 

 matin in old glands. and colors with plasma 



