668 



SCIENCE. 



[N. S. Vol. II. No. 46. 



from a candle passes straight to the retina as usual 

 and forms the image on the central spot of the ret- 

 ina, but the upper marginal rays a are refi'acted 

 upward to 6' on the retina and the lower mar- 

 ginal rays b to «'. These are referred back by 

 the law of direction as shown by the dotted 

 lines. 



Joseph Le Conte. 

 Berkeley, October 30th, 1895. 



Professor Le Conte describes one of the imper- 

 fections in the dioptric apparatus which lead to 

 the formation of entoptic rays of light. In my 

 note to which he refers I only noticed the in- 

 version of the image, and did not attempt to de- 

 scribe the various defects which cause the dis- 

 persion of light, onljr saying, in agreement with 

 Professor Le Conte, that "the light from a gas jet 

 passing through the lower half of the pupil is in 

 part refracted downward, affects the lower half 

 of the retina, and is projected as rays extending 

 upward. ' ' Professor Le Conte' s explanation ac- 

 counts for the vertical dispersal of light when 

 the eyelids are partly closed, but there are 

 other defects in accommodation which lead us 

 to represent a ' star ' not by • but by * . 



I almost hesitate to refer again to the inverted 

 image on the retina. The phenomenon is ex- 

 plained so clearly by Berkeley in his New The- 

 ory of Vision that it ought not to have been re- 

 garded as a puzzle since 1709. What Professor 

 Le Conte has written on the subject in his sug- 

 gestive and valuable book on Sight and recently 

 in this JqxJENAL (p. 629 of this volume) seems 

 to me beside the mark. Our notions of up and 

 down come from sensations of touch and move- 

 ment. A visual image can only be erect or in- 

 verted in reference to other visual images — 

 not in reference to entirely disparate sensa- 

 tions of touch and movement. The image of a 

 man on the retina has the feet towards the im- 

 age of the ground, and this is what we mean by 

 being erect. The retinal image is in any case 



only a link in a chain of physical processes. 

 We do not know how the nerve fibres from the 

 retina are distributed in the brain, but it is 

 highly improbable that they end in a surface or 

 reconstruct in any way a picture or a model of 

 of the external world. 



J. McKeen Cattell. 



SCIENTIFIC LITERATURE. 

 British Association for the A dvancement of Science 

 (Ipswich, 1S95). Tenth Report on the North- 

 western Tribes of Canada. Fifth Report on the 

 Indians of British Columbia. By Fbanz 

 Boas. 71 pp. 8vo. 



This final report of Dr. Boas concludes the 

 investigations, initiated in 1884, which have 

 added so much to our knowledge of the social 

 condition, mental and physical characteristics, 

 languages and institutions of the northwestern 

 tribes of the Dominion of Canada. The main 

 portion of the report is concerned with an ac- 

 count, excellent in detail of presentation, of 

 the ' Physical Characteristies of the Tribes of the 

 North Pacific coast (pages 3-30, besides 11 

 tables of anthropometric data, and many lesser 

 tables in the text)', we have besides notes on 

 the Tinneh tribe of Portland Canal, the Tinneh 

 tribe of Nicola Valley, the Nass River, and 

 brief accounts of the NiskS, (closely related to 

 Tsimshian), and the Ts' Ets' a tit (a Tinneh dia- 

 lect). 



The value and extent of Dr. Boas' contribu- 

 tions to the physical anthropology of the In- 

 dians of the northwest coast may be estimated 

 from the fact that the eleven tables alone con- 

 tain the individual measurement (12 in each 

 case) of some 500 Indians belonging to about 

 a dozen tribes, or subtribes, and to several 

 distinct linguistic stocks. The author's chief 

 conclusions as to physical characteristics are as 

 follows : 



1. There is a gradual decrease in stature as 

 we go southward along the coast from Alaska 

 to Frazer River — the Tlingit averaging 173 cm., 

 the Indians on the shore of Harrison Lake only 

 158 cm. As we go southward the stature in- 

 creases again, but its distribution becomes very 

 irregular. Somewhere between Vancouver 

 Island and the Skeena River a very material 

 change of type takes jjlace. Dr. Boas shows 



