LIFE AND THE CELL 57 



or less degree by many kinds of insects, but where it is conspicuously 

 manifested, as in crickets, katydids and cicadas, it is employed in courtship. 

 In the vertebrates, although there are a few fishes that make noises of un- 

 certain function, the voice proper first appears in amphibians. The breed- 

 ing season in the spring is the time in which the croaking of male frogs is 

 most vociferous, and it has been observed that the females go to the local- 

 ities from which the croaking proceeds. In both the birds and the mammals 

 the voice has acquired other sexual functions, but it still retains its primi- 

 tive employment as a sex call, a function which has received perhaps its 

 acme of perfection in the song of the nightingale. To a certain extent vocal 

 sounds are made in connection with the battles of the males for the posses- 

 sion of the females, as is exemplified by the nocturnal encounters of tom 

 cats and the challenge uttered by the bull moose as he goes on the war 

 path against possible rivals. But in these cases also the use of the vocal 

 apparatus is closely associated with the function of mating. 



With the evolution of parental care the voice comes to be extended be- 

 yond its original sexual function and is employed in different ways in 

 fostering and protecting the domestic group. The danger chirr of the 

 mother quail sends her flock under cover; the cluck of the hen keeps her 

 brood closer around her, and her peculiar call indicative of the discovery 

 of food brings the young chicks to share the prize. And the cry of the 

 young mammal causes the mother to rush to the defense of her offspring 

 or to supply its nutrient wants. Crying, by the way, plays a very impor- 

 tant biological function which human beings share with their humbler 

 mammalian relatives. It is the part of human language which rests upon 

 a basis of pure instinct. It is a call for help prompted by hunger, distress, 

 fear or perhaps merely the desire for attention, as it may come to be in 

 spoiled babies. On the other hand, the response of the mother to the cry 

 of her infant is doubtless prompted by a strong instinctive impulse even 

 in human beings, as it clearly is in lower mammals. 



As social groups came to be evolved, the voice comes to be employed as 

 a means of integrating the activities of the members. Warning cries, grunts 

 of satisfaction in comradeship, cries of distress that bring others to the 

 defense of an animal that is attacked and many other utterances which are 

 instinctively made and instinctively responded to are wide-spread among 

 the higher social and gregarious animals. Finally in man the voice comes to 

 be employed in articulate speech with all that this implies for the further 

 evolution and cultural development of mankind. 



We have already commented on our inability to predict what kind of 

 organic world would have been evolved had it not been for the advent of 

 sex. Very probably its highest products would have been voiceless, and 

 since organs of hearing tend to go along with organs for the production of 

 sound, the creatures would have probably also been deaf. 



I must point out also another line of development which has grown out 



