146 



SCIENCE 



[N. S. Vol. XLIII. No. 1100 



outside the cell varies with the degree to which the 

 tissue is stretched. In studying a large number of 

 acids, no parallelism could be discovered between 

 their rates of entrance into the cell and the order 

 of pigment loss in the different acid solutions. 

 Using the penetration time of acids as a criterion 

 of penetrability (their entrance being shown by 

 the color change of the pigment, which is a 

 "good" indicator for acids), instances have been 

 found in which the speed of aeid penetration is 

 accelerated, while loss of pigment is delayed, and, 

 reciprocally, permeability toward acids may be 

 caused to decrease while the pigment diffuses out 

 of the cell. 



The Doubtful Validity of the Hypothesis of 

 Warning and Immunity Color: W. H. Longlky, 

 Goucher College. 



This paper reports observations upon the color 

 and color-changes of tropical reef-fishes of the 

 West Indian region. The facts noted lead to the 

 conclusions that the color of the fishes is very 

 definitely correlated with their habits and that 

 color-changes are adaptive. Of these ideas both 

 seem incompatible with the conspiouousness hypoth- 

 eses, but neither is at variance with the conception 

 of concealing coloration. 



Rate of Regeneration from New Tissues Compared 

 with that from Old Tissues: Charles Zeleny, 

 University of Illinois. 



When a second removal of the tail of the frog 

 tadpole is made at a level proximal to that of the 

 first removal the tissue at the cut surface is the 

 original old tissue. When the second removal .'s 

 made distal to the first the cells at the cut surface 

 are the newly regenerated ones. The levels of 

 these cuts can be so regulated as to make possible 

 a direct comparison of the rates of regeneration in 

 the two eases. Such a comparison shows that 

 there is no essential difference between the two 

 rates, a slight advantage in favor of the regenera- 

 tion from new tissues being probably not signifi- 

 cant. In one of the experiments the specific 

 amount of regeneration at the end of six days was 

 .196 from old tissue and .204 from new tissue. At 

 the end of eight days the corresponding figures 

 were .303 and .310. 



The result indicates that the primary factors 

 controlling rate of regeneration are not those in- 

 herent in the condition of the cells which prolifer- 

 ate to form the regenerated tail. They are rather 

 to be sought in the influence exerted by other 

 parts of the organism. 



The Function of the Efferent Fibers in the Optic 

 Nerve of Fishes: Leslie B. Arey, Northwestern 



University Medical School. (Introduced by G. 



H. Parker.) 



When the optic nerve only of Ameiurus is sev- 

 ered, the rods, cones and retinal pigment fail to 

 execute their characteristic photomechanical re- 

 sponses. After hemisection of the nerve, move- 

 ments of the elements occur only in that region of 

 the retina adjacent to its intact side. It can not 

 only be shown (since essentially normal responses 

 occur in excised eyes and in eyes attached to the 

 body by the optic nerve only) that a second 

 mechanism exists in association with the muscles 

 innervated by the oculomotor nerve, which inhibits 

 these movements when the optic nerve is cut, but 

 also that electrical stimulation of the peripheral 

 stump of the optic nerve can overcome this inhibi- 

 tion. 



Hence demonstrably functional efferent fibers 

 exist in the optic nerve. Only by the balanced ac- 

 tion of these components with a second extrinsic 

 set of fibers (ciliary nerves?), which independently 

 exert an inhibitory influence upon the movements 

 of the retinal elements, are normal photomechanical 

 responses accomplished. It is probable that ef- 

 ferent impulses in the optic nerve do not directly 

 stimulate the retinal elements to motion, but 

 rather act indirectly by blocking the tonic inhibi- 

 tion exerted by the second system. These efferent 

 optic nerve fibers may be designated as visceral 

 efferent nerve components. 



Severance of the optic nerve of Ahramis or 

 Fundulus does not prohibit movements of the 

 retinal elements, hence it is impossible to state 

 whether the mechanism discovered in Ameiurus is 

 or is not peculiar to that species alone. 

 The Relation of the Body Temperature of Certain 



Cold-blooded Animals to That of Their En- 

 vironment: Charles G. Eogers and Elsie M. 



Lewis, Oberlin College. 



A review of the literature upon the subject of 

 the body temperatures of the so-called cold-blooded 

 animals reveals a lack of uniformity of observa- 

 tions in part, at least, due to faulty methods of de- 

 termination. 



A knowledge of the temperature relations exist- 

 ing between cold-blooded animals and their en- 

 vironments is of importance in all experiments 

 having to do with the determination of tempera- 

 ture coefficients of the rates of reaction of physio- 

 logical processes. If the relation can be shown to 

 be a constant one it is necessary only to control 

 carefully the temperature of the environment in 

 order to have knowledge of the actual tempera- 

 ture of the animal or tissue under observation. 



