the Midwife Toad. 183 
water as is usual with batrachians. It is to be expressly 
noticed that these lumps on the thumbs or arms of male toads 
and frogs are not merely pigmented swellings, but are pads 
bearing numerous minute horny black spines, which are used 
in holding the female in the water. The figures which 
Kammerer gives are quite inadequate, and as they merely 
indicate a dark patch on the thumbs it is not possible to form 
any opinion as to the nature of the structure they represent. 
“The systematists who have made a special study of 
Batrachia appear to be agreed that Alytes in nature does not 
have these structures ; and when individuals possessing them 
can be produced for inspection it will, I think, be time to 
examine the evidence for the inheritance of acquired characters 
more seriously. I wrote to Dr. Kammerer in July 1910, 
asking him for the loan of such a specimen *, and on visiting 
the Biologische Versuchsanstalt in September of the same 
year I made the same request; but hitherto none has been 
produced. In matters of this kind much generally depends 
on interpretations made at the time of observation; here, 
howeyer, is an example which could readily be attested by 
preserved material. I notice with some surprise that in a 
Jater publication [Kammerer, 4] on the same subject no 
reference to the development of these structures is made, 
As these. ... would be of special value in such a diagnosis, 
the omission of any allusion to them calls for explanation. 
Kammerer claims the evidence as proof of Mendelian segre- 
gation in regard to an acquired character, the first example 
recorded. Pending a repetition of the experiment, there is no 
more to be said.” 
A last remark, Kammerer takes it for granted that the 
aquatic parturition, resulting in a strong reduction in the size 
of the vitelline sphere, such as he claims to have artificially 
induced in Alytes, is a case of atavistic reversion (1, p. 70; 
4, pp."96, 105). Has he given sufficient thought to this 
important question? Is he aware of how great a number of 
batrachians, not necessarily with direct development and quite 
irrespective of their systematic position, produce eggs with 
large vitellus, so that, when our knowledge of tropical forms 
-is more advanced, such a type of eggs may no longer have to 
* “Tn reply to my letter, Dr. Kammerer, who was then away from 
home, very kindly replied that he was not quite sure whether he had 
killed specimens of Alytes with ‘ Bruntfischwielen’ or whether he oul 
had living males of the fourth generation, but that he would send illus- 
trative material.” 
