2o 4 PROBLEMS OF GENETICS 



in many ways, but the essential statements are, as regards 

 S. maculosa, that when no water was provided in which the young 

 might be born, they were dropped on land, larger and in a later 

 stage of development and of a darker colour than is normal; that 

 the larvae so born gradually diminished in number until only 

 two were deposited in each breeding-period; that dissection 

 showed that the other ova degenerated to form a yolk-material. 

 The larvae so produced reached maturity. The summary of 

 results describes their behaviour, stating that they produced: 



(a) In water, either (i) very advanced, large-headed larvae 

 45 mm. long (instead of 25-30 mm.) with gills already reduced, 

 which had awkward, embryo-like movements, and in some few 

 days metamorphosed into small perfect salamanders; or (2) 

 moderately advanced, properly proportioned larvae, 40-41 mm. 

 long, provided with large gills of (at first) intrauterine character, 

 which were reduced during aquatic life. 



(b) On land, small (26 mm. long) larvae with rudimentary 

 gills, having the body rounded instead of being flattened from 

 above downwards, and an elongated narrow head, which were 

 unable to live in deep water. These larvae changed to the sala- 

 mander colour in 10-12 days, and after four weeks metamor- 

 phosed into salamanders 29 mm. long. 



(c) In the foregoing cases the experimental conditions were 

 not continued, or in other words, basins of water were provided 

 in which they could spawn. But if the experimental conditions 

 are continued, these Salamandra maculosa which were born 

 newt-like (viz., not in a larval condition), are themselves newt- 

 bearing from the first time they give birth, using the dry land, 

 and bringing forth only two young, the normal number for the 

 births of 5. atra. These young are 40-41 mm. long, and are 

 dark-coloured, resembling greatly the normal new-born S. atra. 



This epitome of the observations illustrating the inheritance 

 of acquired characters has been very widely quoted, and may 

 not unnaturally be taken to summarize a wide experience of 

 the modified animals. Reference to the details given in the 

 same paper shows that, as alleged, each of the four types of be- 

 haviour enumerated was witnessed once only in the case of each 



