It has been mentioned already that the mature male frogs and toads possess during the breeding season lumps on the thumbs or arms which are pigmented and which bear numerous minute horny black spines; these secondary sexual characters serve the male frog in holding the females in the water during copulation. There is one species which does not possess this sexual character, namely the male of the so-called midwife toad (_Alytes obstetricans_). In this species the animals copulate on land, and it is natural to connect the lack of this secondary sexual character in the male with its different breeding habit. Kammerer now forced such toads to copulate in water instead of on land (by keeping the animals in a terrarium with a high temperature). He makes the statement that by forcing the parents to lay their eggs during successive spawning periods in water he finally obtained offspring which under normal temperature conditions lay their eggs naturally in water; in other words, they have changed their habits. We will not discuss this part of his statement since the breeding habits of animals in captivity are liable to be abnormal. But Kammerer makes the further important statement[287] that the male offspring of such couples will in the third generation produce the swelling on the thumb and the usual roughness, and in the fourth generation black pads and hypertrophy of the muscles of the forearm will appear. In other words, he reports having succeeded in producing an inheritance of an acquired morphological character which has never been known to occur in this species. Bateson, on account of the importance of the case, wished to examine it more closely and I will quote his report. 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, however, is an example which could readily be attested by preserved material.[288] [287] Kammerer, P., _Arch. f. Entwcklngsmech._, 1909, xxviii., 448. [288] Bateson, W., _Problems of Genetics_, pp. 201-202. Yale University Press, 1913.