The Evolution of Parental Care 41 



in pouches on the back or in sacs connected with the 

 throat. One of the most peculiar cases is afforded 

 by the obstetrical toad of Europe in which the male 

 carries the string of eggs coiled about his hind legs 

 until the young are ready to hatch. 



While the Amphibia in some cases exhibit a cer- 

 tain care for their eggs, they all appear to be utterly 

 indifferent to their young. One reason for this is 

 the fact that the young usually live in the water 

 while the parents are often terrestrial, but another 

 reason is doubtless to be found in the low psychic 

 development of these animals. 



Reptiles as a class concern themselves very little 

 about their progeny. The latter are quite well able 

 to take care of themselves upon their first introduc- 

 tion into the world. Alligators are said to watch ^ 

 over the places where their eggs are buried in the 

 sand, and pythons coil around their eggs and help to ^ 

 incubate them by the warmth afforded by their bodies. 

 Solicitude for their eggs is, however, very rare 

 among the reptiles, and active care for their young 

 is practically absent. 



With the birds, which as a group are remarkable 

 for their parental and fostering instincts, care for 

 the eggs appears to be universal, and with rare ex- 

 ceptions the birds sit upon the eggs until they are 

 hatched. There has been much speculation concern- 

 ing the origin of this curious instinct of incubation. 

 As Whitman has remarked, "the incubation instinct 

 was supposed to have arisen after the birds had ar- 



