Care of the Young in the Animal Kingdom. 163 



ing its cell and giving it different food.^ Also in the 

 case of termites, so we are informed by Grassi and 

 Sandias,^ the various methods of nursing the larvae, 

 and especially the different salivary gland secretions of 

 the nurses are of great importance in the differentia- 

 tion of the castes of one and the same species. The 

 same probably holds good with ants,^ and, indeed, with 

 far more variability than with honey-bees, although less 

 than with termites. This is indicated by the numerous 

 intermediate forms between the females and workers 

 of ants.* Of course, wherever these appear, they are 

 exceptional forms, yet none the less they throw some 

 light on the origin of the normal differentiation into 

 females and workers; for, their existence is most 

 intelligible on the supposition, that the difference of 

 caste is not predetermined in the egg, but that it will 

 depend on the nursing, whether the fertilized egg will 

 bring forth a winged, perfect female, a normal worker 

 or perhaps some intermediate form. 



Of course, the specific development peculiar to 

 every ant-species Is the necessary foundation for the 

 differentiation of the normal castes and for the origin 

 of certain abnormal, intermediate forms. Where there 



1) Cf. N. Ludwig, "Futtersaft oder thierische Veranlagung." — 

 According to Planta's tables the food of queen-bees contains a far 

 larger amount of fat. But according to Ludwig it is especially the 

 different quality of the saliva, added by the bees to the nutrifying 

 juice, which is of decisive importance. 



2) "Costituzione e sviluppo della Societa dei Termitidi" (Catania, 

 1893), pp. 75-106. 



3) Emery, "Le Polymorphisme des fourmis et la castration alimen- 

 taire," Leyden, 1896 (Extr. du Compte rendu des Seances du 3me 

 Congres internat. de Zool., p. 395 ff.). 



*) Wasmann, "Die ergatogynen Formen bei den Ameisen und ihre 

 Erklaerung" ("Biolog. Centralbl.," 1895, Nos. 16 and 17). 



