Decembee 3, 1909] 



SCIENCE 



809 



received througli the ear and caused by vibrations 

 either in the air or water, the experiments cited 

 do not enable one to conclude definitely whether 

 the blind fishes hear or not. If they do hear, 

 their power in this direction is very limited. 



Twelve species of blind fishes are dealt with. 

 One, Typldogohius californiensis, found under 

 the rocks at Point Loma, near San Diego, 

 Cal., has normal eyes when young, but de- 

 generate in the adult. Another, a blind cat- 

 fish {Amieurus nigrilahris) from Pennsyl- 

 vania, is briefly described by Cope. The 

 remaining ten species of blind fishes were 

 procured from the eaves of central and south- 

 western United States and from Cuba. Eight 

 of these belonging to the Amblyopsidae (" blind 

 fishes ") inhabit Xorth America. The other 

 two, members of the Brotulidse, were secured 

 in the caves of Cuba. 



Of the Amblyopsidae three species of Cholo- 

 gaster (cornutus, papalliferus and agassizii) 

 have well-developed eyes. The other species 

 of Amblyopsidae, Amhlyopsis spelmus, Trog- 

 lichthys rosce, Typhlichthys suhterraneus, 

 Typhliclithys oshorni and Typhlichthys Wyan- 

 dotte, have only vestigial eyes. 



The two Cuban species, Stygicola and Luci- 

 fuga, were both found to be viviparous. Xo 

 definite breeding season could be determined, 

 as females with young were found at various 

 times throughout the year. " The eye de- 

 creases in size progressively from birth to 

 extreme old age concomitantly with the ap- 

 pearance of masses of pigment cells in the 

 orbital fat." Shriveling may occur in one 

 eye of an individual while the other may show 

 a massing of pigment cells. All structures 

 connected with the eye show this progressive 

 reduction from birth to old age. 



The closing chapter discusses the causes of 

 individual and phyletic degeneration. The 

 following views of others concerning the cause 

 of degeneration are discussed : (1) Organs 

 diminish with disuse (Lamarck, Eoux, Pack- 

 ard) ; (2) through a condition of panmixia a 

 reduction occurs (Romanes, Lankester, ilor- 

 gan, Weismann) ; (3) natural selection (Dar- 

 win, Romanes) ; (4) struggle of organs for 

 room and food (Roux, St. Hilair) ; (5) the 



struggle between soma and germ for greatest 

 efficiency at least expense (Lendenfeld) ; (6) 

 germinal selection (Weismann), (7) process 

 of mutation. 



The author's views of the causes of degen- 

 eration may best be given in his own words: 



The Lamarckian view, that through disuse the 

 organ is diminished during the life of the indi- 

 vidual, in part at least on account of the diminu- 

 tion of the amount of blood going to a resting 

 organ, and that this efi'ect is transmitted to suc- 

 ceeding generations, not only would theoretically 

 account for unlimited progressive degeneration, 

 but is the only view so far examined that does 

 not in the face of it present serious objection. 

 Is this theory applicable in detail to the condi- 

 tions found in the Amblyopsida; ? Before going 

 farther, objections may be raised against the 

 universal assumption that the cessation of use 

 and the consequent panmixia was a sudden process. 

 This assumes that the caves were peopled by a 

 catastrophe. But it is absolutely certain that the 

 caves were not so peopled, that the cessation of 

 use was gradual and the cessation of selection 

 must also have been a gradual process. There 

 must have been ever widening bounds within 

 which the variation of the eye would not subject 

 the possessor to elimination. 



Chologaster is in a stage of panmixia as far as 

 the eye is concerned. It is true the eye is still 

 functional, but that the fish can do without its 

 use is evident by its general habit and by the 

 fact that it sometimes lives in caves. 



The present conditions have apparently existed 

 for many generations, as long as the present 

 habits have existed, and yet the eye still main- 

 tains a higher degree of structure than reversed 

 selection, if operative, would lead us to expect, 

 and a lower degree than the birth mean of fishes 

 depending on their eyes — the condition that the 

 state of panmixia alone would lead us to expect. 

 There is a staying quality about the eye with the 

 degeneration, and this can only be explained by 

 the degree of use to which the eye is subjected. 



Three general conclusions may be added: 

 (1) The bleached condition of animals living in 

 the dark, and individual environmental adapta- 

 tion, is transmissible and finally becomes heredi- 

 tarily fixed. (2) Ornamental secondary sexual 

 characters not being found in blind fishes are, 

 when present, probably due to visual selection. 

 (3) Individual degeneration of the ej-e may begin 

 in even earlier stages of development until nearly 



