Affective Tendencies 379 



at first simply endured by one of the parents, either 

 father or mother, finally become actual "needs" to this 

 parent. 



It is likewise true of the relations of external incuba- 

 tion (brooding) which arise at first as the result of some 

 particular circumstance and in this way become a habit. 

 For instance the attachment manifested by the female 

 spider Chiracanthium carnifex for her nest, whether it 

 be her own or one of which she has taken possession, 

 grows with time, that is with the length of her occu- 

 pation of it. Hence "mother love" seems in her case 

 to be really nothing but her attachment to a home to 

 which she has become accustomed. 20 



It is just the same with the brooding of birds and 

 some reptiles, \vhich owes its origin to the pleasant sen- 

 sation which the contact with the fresh eggs brings in 

 the feverish condition accompanying the egg-laying 

 process, but which by habit has become in itself an in- 

 stinctive inclination. 21 



Finally as regards lactation the young have gradually 

 developed secretions in the lactiferous glands by sucking 

 the secretions of the perspiratory glands on the breast of 

 the mother brooding over them, and thus they have at 

 the same time so accustomed the mother to this process 

 that lactation finally becomes an actual need for her. 

 "With mammals we must look for the origin of the 

 mutually symbiotic relations which unite mother and 

 child in the phenomenon of lactation. The physiological 

 disorders of pregnancy and parturition lead, among other 

 very curious trophic effects, to an excessive secretion of 



20 A. Lecaillon, "Sur la biologic et la psychologic d'une araignee," 

 Annee psycholtigique, Annee ice, pp. 63-83. Paris, Nasson, 1904 

 21 Giard, op. cit., p. 266. 



