256 INEZ WHIPPLE WILDER. 



The part which the shaded condition plays in the habitat of 

 Desmognathus is undoubtedly a somewhat complicated one, 

 possibly determining conditions for the necessary food supply, 

 as well as helping to maintain a moist condition of the soil, 

 supplying an abundant and annually replenished loose earth 

 from fallen leaves and twigs; those leaves, also, which fall into 

 the water furnish lurking places in which the larvae take refuge 

 and seek their food. The element of close proximity to running 

 water in the habitat of Desmognathus is certainly not necessary 

 to the immediate physiological demands of the adult, but is 

 incident rather to the aquatic nature of the larval life, which 

 makes necessary not only easy access to water after hatching, 

 but also requires that the supply of water shall be perennial, 

 since each year the newly hatched larvae reach the water at about 

 the time when the brood of the previous summer leave the water 

 as very small adults. Upon the other hand, these small adults 

 upon leaving the water find themselves in the midst of the proper 

 external conditions for their whole adult life, including mating 

 and egg laying, and therefore, so far as is known, there is no 

 tendency whatever to annual migrations such as has been shown 

 to occur in Amblystoma punctatum, for example (Wright, '08). 



MATING HABITS. 



In his valuable discussion of the breeding habits of amphibians, 

 Smith ('07) has pointed out an interesting gradation in methods 

 of fertilization from the lavish method of typical aquatic fertili 

 zauon oos?essed bv Cryptobranchus, in which the unfertilized 

 eggs are expened into the water in large numbers, to take their 

 chances at being fertilized by the abundant spermatic fluid 

 expelled by the male in their vicinity, to the opposite extreme of 

 typical internal fertilization without spermatophores, which the 

 Apoda have been shown to have acquired as an adaptation to 

 their completely terrestrial existence. Between these two 

 extremes lie such forms of fertilization as that of the Amblys- 

 stoma punctatum, in which the spermatozoa are not poured 

 freely into the water, but are enclosed within spermatophores 

 which the male, stimulated by the presence of the ripe or nearly 

 ripe female, deposits in considerable numbers, leaving with the 



