182 ilr. G. A. Boulengev on 



There is anotlier criticism — one of tlie most important — 

 wliicli Kammerer has not yet answered. 



Having bred the "water-form " to a fourth generation, this 

 is what he claims to have observed : — 



" Es zeigt sich aber an den geschleclitsreifen Mlinnchen 

 vierter Generation eine weitere mor[)hologische Variation . . . 

 wareu die briinftig gewordenen Miinnchen alle mit schAvarzen 

 verfiirbten Schwielen an der Oberseite des Daumens und am 

 Daumenballen versehen und ebenso zeigt sich an ihnen eine 

 Hypertrophic der Vorderarmmuskulatur " (2, p. 516, fig. 26). 



When I first saw the figure of the male Alytes with black 

 nuptial callosities on the "Daumen" or inner finger I con- 

 cluded that such a disposition was highly improbable, if not 

 impossible, basing my opinion on the small size and the 

 shape of this finger in normal individuals, and I have since 

 satisfied myself, by handling a pair in amplexUj that, if 

 callosities should ever develop on tlie fingers, they would 

 be on tlie two inner fingers, botli being in contact with 

 tlie inguinal region of the female — a correlation to which I 

 know of no exception. It is true that Kammerer appears to 

 have been under the erroneous impression that the thumb 

 alone plays a role in theamplexus in all European Anura : — 

 " J3ekanntlich steigt das Anurenraaiinchen seinem Weibchen 

 aufc' den Riicken und umklammert es, indem es seine Daumen 

 bald in die Lenden bald in die x\ciiselgrube des Wcibcheus 

 einstemmf (4, p. 100). 



As I told Prof. Bateson at the time, if a specimen such as 

 is figured could be produced, I would cease to doubt any of 

 Kauimerer's statements. This is how the matter now stands, 

 according to Bateson * : — 



" Regarding the Alytes bred in this way " [alleged atavistic 

 reversion to aquatic breeding-habits] "Kammerer makes tlie 

 very striking statement that the males in the third generation 

 have rouf/hened swellings on their thumbs and that in the 

 fourth generation these swellings develop blade p2_^wg«^. 

 Together with the appearance of this secondary sexual 

 character there is hypertrophy of the muscles of the fore arm. 

 To my niind this is the critical observation. If it can be 

 substantiated it would go far towards proving Kammerer's 

 case. Alytes, among toads and frogs, is j)ecuiiar in that the 

 males do not develop these lumps in the breeding-season, and 

 the fact may no doubt be taken to be correlated with the 

 breeding-habits, copulation occurring on land, and not in 



* ' Problems of Genetics' (New Hayen auJ Loudon, 1913), p. 201, 



