Literary Notices. 525 



has done her work with commendable care, but despite this fact many minor errors 

 appear in the text. 



It is to be noted in this connection that VON Buttel-Reepen has recently pub- 

 Hshed,' in the form of a monograph, the resuhs of several years of work on the 

 biology of the honey bee. 



Cole, Leon J. An experimental Study of the Image-Forming Powers of Various Types of Eyes. 

 Proc. of the Amer. Acad, of Arts and Sciences, vol. 42, pp. 335-417. 1907. 



The image-forming power is here studied not directly, but indirectly by means of 

 the responses of the animals in question to light-stimuli of equal intensity but unequal 

 areas. The apparatus was so arranged that the individual under investigation 

 was free to move either toward a small source of hght or (in the opposite direction) 

 toward a luminous field of about 10,000 times the area but of the same total inten- 

 sity. This intensity varied in the course of the experiments from 5 to 1 .25 candle 

 meters. Thus an animal which can form no optical image of a source of light and 

 which responds therefore to intensity alone, would respond to either of the stimuli 

 here offered, indifferently. And this was found to be the case in an eyeless form, 

 the earthworm. 



Animals having "direction eyes" (Bipalium kewense, Periplaneta americana, 

 larva of Tenebrio molitor, and larva of the wood-borer) were found to respond 

 almost wholly to intensity of light. The few doubtful cases are explicable, since 

 certain forms and arrangements of direction eyes "may be considered as the 

 beginning of a crude image-forming apparatus" (p. 362). Animals with image- 

 forming eyes (Vanessa antiopa, Ranatra fusca, Acris gryllus, and Rana clamata) 

 were found to be mostly positive; they move toward the stimulus of larger area. 

 Whether positively or negatively phototropic, their preference for the smaller or the 

 larger simulus was well marked. 



The author studies and discusses many more than the above-mentioned species, 

 both experimentally and from the available literature. In pp. 402-412 are pre- 

 sented several interesting theoretical considerations, particularly those relating to 

 three types of response, to intensity of light, to luminous area, and to "definite 

 objects." The investigation is ingenious, careful, and suggestive. 



E. B. H. 



'Apistica. Beitrage zur systematik Biologic, sowie zur geschichtlichen und geographischen Ver- 

 breitung der Honigbiene {Apis mellifica, L.), ihrer Varietaten und der iibrigen Apis-Arten. 

 Mittfi. d. kgl. Zool. Museums, Berlin. 1906. 



