I 78 LEO LOEB. 



of a litter or mother and mate, but individuals of the same species 

 as such. This problem does not seem so far to have been con- 

 sidered by students of animal behavior. At least inquiries which 

 I made among some prominent investigators in this field, failed 

 to provide any definite data which might be used in this connec- 

 tion. From my own observations I am very much in doubt as 

 to the ability of such animals as the common rodents to discern 

 individuality in the sense in which we defined it. There seems 

 to be little doubt on the other hand that higher animals like dogs 

 and horses have such an individuality discernment, at least to a 

 certain extent. 



It is then very probable that the mechanisms which permit the 

 ordinary tissue cells to discern and to react towards individuality 

 have developed much in advance of that mechanism of our nerv- 

 ous system which permits us to recognize individuals in a con- 

 scious manner. On the other hand after the latter faculty has 

 once developed, it has reached in man a very much greater de- 

 gree of refinement in individualization than that exhibited by the 

 discernment of individuality on the part of cells in general. 



LITERATURE. 

 Baltzer, F. 



'10 Arch. f. Zellforschung, V., 497. 

 Born, G. 



'97 Arch. f. Entwickelungsmech., IV., 349. 

 Braus, H. 



'06 Arch. f. Entwickelungsmech., XXII., 564. 

 Crampton, H. E. 



'oo Arch. f. Entwicklungsmech., IX, 293. 

 Driesch, H. 



'oo Arch. f. Entw.-mech., X., 411. 

 Dungern, Von. 



'19 Munch. Med. Wochenschr., L., VII., 293-74- 

 Fleisher, Moyer S., and Loeb, Leo. 



'16 Journal Cancer Research, I., 331. 

 Goldfarb, J. 



'15 Arch. f. Entw.-mech., XL.. I., 579. 

 Guyer, M. F. 



'12 Journ. Morph., XXIII., 45. 

 Harms, W. 



'12 Arch. f. Entw.-mech., XXXIV., 90, 1912-13, XXXV., 748. 

 Hektoen, L. 



'07 Journ. Inf. Diseases, IV., 297. 



