5o THE POPULAR SCIENCE MONTHLY 



A third series of experiments was tried on two European sala- 

 manders, Salamandra ater and Salamandra maculosa. The former is a 

 black mountain salamander which has the peculiar habit of bringing 

 forth its young alive, always a brood of two with lungs already func- 

 tional. The embryos pass through their early development in the body 

 of the mother, nourished by the yolk of eggs that fail to develop. 

 Salamandra maculosa is a yellow-spotted salamander of the lowlands 

 which lays its eggs in running brooks. When kept away from the 

 water the female of the spotted salamander at first dropped her eggs 

 on the ground directly after fertilization. Such eggs failed to develop. 

 In the course of two years, however, this salamander gradually ac- 

 quired the habit of holding the eggs in the body for several weeks. 

 The eggs became fewer in number and larger in size until the young 

 were brought forth alive in a condition like that of the black sala- 

 mander. Females of the latter were treated in an exactly opposite 

 way. They were kept in or near the water until they acquired the 

 habits of the spotted salamander. Inheritance was imperfect in each 

 case. The new type of spotted salamander, under the usual normal 

 conditions, deposited in the water a brood of five fairly well developed 

 young. The new type of black salamander, under normal conditions, 

 deposited in the water a brood of three young in a stage of develop- 

 ment more advanced than that of the spotted salamander. When the 

 artificial conditions of the experiments were continued through two 

 generations the effect was greater. The author claims that his experi- 

 ments show the inheritance of acquired characters influencing structure 

 and instinct. 



A second experiment was tried on Salamandra maculosa to test the 

 inheritance of acquired color due to change of background. A brood of 

 young salamanders was divided into two lots, one of which was kept for 

 six years on a background of yellow, the other on a background of 

 black. The former showed a decided increase in yellow markings, the 

 latter an increase in black markings. The young of the yellow type 

 were allowed to begin their development on a background of neutral 

 tint, but before reaching maturity the brood was divided as before into 

 two parts and placed, one part on a yellow background, the other on a 

 black background. The set on yellow, after two years, showed a great 

 increase of the yellow markings as compared with their parents, in 

 fact the yellow pigment nearly covered the body. The set on the black 

 background showed more black than their parents, but less black than 

 the previous set similarly treated but of normal parents. These experi- 

 ments, according to the author, show the progressive effect of environ- 

 ment in the inheritance of acquired colors. 



The evidence presented by these experiments, which have been 

 briefly described in the preceding paragraphs, should be considered in 



