INHERITANCE OF ACQUIRED CHARACTERS. 445 



uterus and placed in water, they cast off their richly vascular 

 long red gills and regenerate in their place stouter branched 

 gills like those of the larvae of S. maculosa. Moreover, if females 

 of S. atra are collected from the lower habitats and kept in warm 

 conditions they often naturally deposit their young in the water 

 in the larval stage, and these young are usually more than two 

 in number. On the other hand, females of S. maculosa, which 

 are deprived of the opportunity of depositing their young in the 

 water, detain them to their final metamorphosis in the uterus. 

 The nourishment in this case is exactly similar to that which 

 normally takes place in S. atra, only a few embryos surviving, 

 the rest breaking down to form a vitelline mass. These intra- 

 uterine embryos differ from the normal free-swimming larvae at 

 the same age in their possession of long vascular gills. Their 

 tail-fins are very small, and they retain their primary dark 

 colour. 



After metamorphosis these animals are still distinguished 

 from normal S. maculosa of the same age by their smaller size 

 and the lesser number of the yellow spots on the black back- 

 ground. Young S. maculosa, however reared, if kept on black 

 earth at a low temperature and with little moisture, exhibit a 

 preponderance of the black ground colour at the expense of the 

 yellow spots. On the other hand, if young S. atra are kept 

 on a clayey soil at a relatively high temperature and in a 

 nearly saturated atmosphere, small whitish points appear on the 

 skin, which sometimes expand into small yellow spots. 



Salamandra maculosa can also be modified in the opposite 

 direction, and become truly oviparous. This occurs if the female 

 is stroked, or if she is kept in a completely saturated atmosphere, 

 or if she is placed suddenly in ice-cold water. If the same in- 

 dividual is treated in this manner for several spawning periods, 

 she eventually acquires the habit of laying her eggs early, even if 

 the stimulus is not applied. From eggs obtained in this way 

 the larvae do not emerge for about a fortnight, and when hatched 

 only possess the anterior pair of limbs, though the posterior 

 appear the following day. 



Under the same influences Salamandra atra can be got to 

 produce her larvae in the water in the larval stage, and then 

 prives birth to from three to nine at a time instead of two. If 



