432 



SCIENCE 



[N. S. Vol. XXIX. No. 741 



spectrum produced the largest number of positive 

 responses from normal salientians, no such potency 

 was manifested by the shorter rays when eyeless 

 individuals were tested. In the latter case all 

 rays were equally effective in inducing reactions. 



Eyeless toads which gave marked phototropic 

 responses were indifferent to radiant heat of an 

 energy value equivalent to that of the light used. 

 It may, therefore, be affirmed that thermo- and 

 photo-reception are distinct processes in the toad's 

 SKin. 



Spinal amphibians gave no photic responses, but 

 light reactions were induced in animals which had 

 lost the portions of the brain anterior to the 

 metencephalon. 

 The Beceptiveness of the Vertebrate Skin for 



Light and the Origin of the Vertebrate Eye: 



6. H. Pabker, Harvard University. 



In the last few years it has been shown that 

 numerous amphibians will respond to light by 

 moving either toward it or away from it even 

 after their eyes have been removed. The receptive 

 organ in this response is the skin. Tests of a like 

 kind have been made on only a very few fishes. 

 It is highly probable that the skin of Amphioxus 

 and of Fundulus is not sensitive to light and it is 

 very certain that that of ammocoetes is highly 

 sensitive to this stimulus. To ascertain the con- 

 dition in other fishes, blind individuals of nine 

 species of marine forms were tested by throwing 

 upon the side of the body a beam of concentrated 

 sunlight. The species tested were Mustelus canis, 

 Anguilla chrysypa, Fundulus heteroclitus, Steno- 

 tomus chrysops, Tautogolabrus adspersus, Tautoga 

 onitis, Ghilomyoterus schwpfi, Opsanus tau and 

 Microgadus tomcod. In no instance was any reac- 

 tion observed. As all these species and Amphi- 

 oxus are marine and the amphibians and ammo- 

 coetes are inhabitants of fresh water, it seems as 

 though fresh water was favorable for the develop- 

 ment of integumentary sensitiveness to light and 

 salt water inimical to this. The condition may be 

 just the reverse of animal phosphorescence which 

 is common in the sea, but unknown in fresh water. 

 If further investigation should prove that no 

 marine vertebrate has an integument sensitive to 

 light, such theories of the origin of the vertebrate 

 eyes as derive it from the skin would be rendered 

 highly improbable. 



Methods of Studying Color Vision in Animals: 

 Robert M. Yerkes, Harvard University. 

 There are three general methods of obtaining 

 chromatic stimuli: the reflection method (absorp- 

 tion and reflection by colored papers, cloths, pig- 



ments), the transmission method (absorption and 

 transmission by colored glasses, gelatines, solu- 

 tions) and the refraction method (dispersion spec- 

 tra by means of prism). 



Of these three methods, the first is purely quali- 

 tative, and has as its chief recommendation the 

 naturalness of its stimuli. The second method is 

 both qualitative and quantitative, but it fails to 

 give the experimenter that degree of control of 

 the wave-length of his stimulus which is demanded 

 by the thoroughgoing and rigidly scientific quan- 

 titative investigation. The third method promises 

 to meet the chief requirements of quantitative 

 work. 



These requirements are that the method shall 

 enable the experimenter ( 1 ) to obtain stimuli 

 of any desired wave-length or range of wave- 

 lengths, (2) to measure the wave-length of the 

 stimuli accurately and with reasonable facility 

 (preferably by means of a calibrated slit mechan- 

 ism), (3) to control the intensity of the stimuli 

 perfectly by (a) moving the source of light, or 

 (6) changing the size of the beam, or (c) inter- 

 rupting the beam, or by each of these methods in 

 turn, (4) to measure the intensity of stimuli 

 accurately and easily both photometrically and 

 radiometrically (preferably by means of a cali- 

 brated mechanism), (5) to present chromatic 

 stimuli to his subject independent of the second- 

 ary criteria of discrimination: size, form, dis- 

 tance, position, texture of surface and temperature. 



Investigations now in progress in the psycho- 

 logical laboratories of Harvard and Johns Hop- 

 kins universities, under the direction of the com- 

 mittee on standardization of tests appointed by 

 the American Psychological Association, promise 

 to provide us soon with an admirable method for 

 the study of color vision in animals. A report of 

 the results of these investigations is now in course 

 of preparation by R. M. Yerkes, J. B. Watson and 

 E. D. Congdon. 

 An Account of Experiments for Determining the 



Complete Life History of Gasterostomum gror 



cilescens: D. H. Tennent, Bryn Mawr College. 



In previous work' the writer demonstrated the 

 life history of Oasterostomum gracilesoens with 

 the exception of infection of the oyster. 



During the summer of 1908 I obtained Lepi- 

 sosteus osseu-s from the region of oyster beds i.i 

 Newport River, North Carolina, and found that 

 they contained Oasterostomum in abundance. 

 The faeces of the fish were found to contain Gas- 

 terostomum embryos. 



' Quart. Jour. Mio. Sci., Vol. 49, pp. 635-690. 



