EFFECTS OF CHANGED ENVIRONMENT 215 



temperature. It should also be noted that in many butterflies 

 there is a strong constitutional i.e. germinal tendency to 

 melanistic variation, that the aberration does not occur in all the 

 individuals subjected to the low temperature, that it occurs in 

 very diverse degrees, and that the experimenter selected two forms 

 to pair together. 



Fresh Experiments. Among the twentieth-century experi- 

 ments on the transmission of modifications, there are a few 

 which suggest that a dogmatic denial of the possibility is very 

 unwise. 



Kammerer has made some striking experiments on Amphibians 

 (Archiv. fur Entwicklungsmechanik , 1898-1914). 



(1) He kept the spotted salamander (Salamandra maculosa) in 

 the cold and got it, after a few births, to produce, instead of the usual 

 numerous larvae or numerous eggs, two young ones, as in the black 

 salamander (S. atra) of the Alps. The offspring of these spotted 

 salamanders kept in normal environment gave birth to very ad- 

 vanced larvae showing a partial persistence of a modified form of 

 reproduction in the absence of the modifying conditions. Other 

 results of the same kind were obtained. 



(2) Young salamanders on a yellow floor became yellower than 

 usual, and their offspring exposed to the same influences were 

 yellower still. But some of these offspring reared on a black floor 

 showed themselves yellower than usual for the first six months of 

 their life, till the black pigment began to predominate. 



(3) The Nurse Frog, Alytes, normally pairs on land, and the male 

 has no horny pad on its hand for gripping the female. Kammerer 

 induced the frog to pair in water, and after several generations 

 males with swollen pads were produced. 



(4) W. E. Agar (Philosophical Transactions, Roy. Soc., 1913) 

 subjected a small water-flea (Simocephalus) to peculiar environment 

 and induced a peculiar modification. ' After eggs had appeared 

 and grown in the ovary, the little crustaceans were restored to nor- 

 mal water. In due time the eggs developed, but the offspring showed 

 the parental modification. When the parents laid again, the 

 abnormal feature was seen in the offspring in a slight degree ; in a 

 third brood it had dwindled away. It is probable that the original 

 peculiarity of nurture resulted in the production of some peculiar 

 non-living metabolic product, which was included in the cytoplasm 



