November 14, 1913] 



SCIENCE 



699 



other hand, occur when the pairs of factors 

 involved lie in different chromosomes. The 

 method by vrhich the location of loci (factors) 

 in the chromosomes is calculated will be ex- 

 plained. 

 H. McL. Evans: The Action of Vital Stains 



Belonging to the Benzidine Group. 

 S. O. Mast : Changes in Pattern and Color in 



Fishes, with Special Reference to Flounders. 



The flounders ordinarily lie on the bottom 

 and the skin assumes a color and pattern so 

 nearly like that of their environment that it 

 is frequently difficult to see them. On a black 

 bottom they become black, on a white bottom 

 white, on a yellow bottom yellow, on a blue 

 bottom bluish, on a red bottom reddish, etc. 

 All of these changes in the skin are regulated 

 through the eyes. This indicates color vision. 

 If the bottom is finely mottled the pattern in 

 the skin assumes a fine grain; if coarsely 

 mottled, it assumes a coarse grain. But there 

 is no evidence indicating an actual reproduc- 

 tion of the configuration of the background. 

 If, after the skin has become adapted to a 

 given bottom, the fish are moved to a different 

 bottom they tend to return to the original. 

 That is, they tend to select a bottom which 

 harmonizes with their skin. 

 D. S. Johnson: The Perennating Fruits of 



the Prichly Pears. 



The fleshy fruits of certain prickly pears are 

 not shed, as most fruits are, but remain 

 attached for ten years or more. These fruits 

 continue to grow by a cambium and, while 

 they remain attached, their axillary buds give 

 rise to flowers only. If, however, the chains of 

 fruits thus formed are separated from the plant 

 their buds give rise only to roots and vegeta- 

 tive joints. The plants are propagated in this 

 way. Seeds, though sometimes formed, have 

 never been seen to germinate. 

 B. F. Lovelace: A Static Method for the 



Measurement of Vapor-pressures of Solutions. 



The method is based upon the principle of 

 the Rayleigh manometer. Vapor from solvent, 

 carefully freed from air, is admitted to one 

 limb of the manometer and vapor from solu- 

 tion to the other limb. The manometer is con- 

 structed to give a sensibility of 0.0005 milli- 



meter and readings are made in the usual way 

 by means of a telescope and scale. Provision 

 is made for stirring the solution, also for re- 

 moving air to less than 0.0004 millimeter 

 pressure, the pressure in system due to air 

 being measurable at any time during the prog- 

 ress of an experiment. 



H. C. Jones: The Absorption of Light hy 

 Water Containing Strongly Hydrated Salts. 

 Salts, such as magnesium and calcium 

 chlorides, which, in aqueous solution combine 

 with a large amount of the solvent, diminish 

 the power of water to absorb light. Unhy- 

 drated salts, such as potassium and ammonium 

 chlorides, produce no such effect. This would 

 indicate that water combined with a dissolved 

 substance has less power to absorb light than 

 free water. This fact is in keeping with a 

 number of others which have recently been 

 brought to light ; and they all seem to point to 

 the general correctness of the solvate theory 

 of solution. 



Simon Flexner: Some Factors in the Epi- 

 demiology of Infection. 

 Knight Dunlap: The Fusion of Successive 

 Flashes of Light. 



The least perceptible interval between two 

 light stimuli is dependent on several factors, 

 among which is the relative duration of the 

 stimuli and the dark interval. As determined 

 in extensive preliminary experiments with a 

 beam of light interrupted at its focus by a 

 properly sectored rotating disc, the least per- 

 ceptible interval ranges from approximately 

 20 o- when the two stimuli are equal in length 

 to the dark interval, dovni to 4 o- when the 

 stimuli are 18 times the length of the inter- 

 vening interval. This variation is principally 

 a function of the length of the first stimulus, 

 the length of the second stimulus having a 

 slight effect of different character. Corre- 

 sponding measurements for flicker give some- 

 what lower results, namely, from approximately 

 11 0- to 2 (7. The difference in these measure- 

 ments is readily explained. 

 J. J. Abel : Demonstration of an Artificial 



Howard A. Kelly : Radio-therapeutics in 

 Surgical Affections. 



