No. 3.] PHENOMENA OF SEX-DIFFERENTIATION. 491 



the union of two sexual cells is itself the inevitable consequence 

 of the sexual differentiation of the organism at the outset. 

 Thus, instead of the necessity of the union of the germ-cells 

 being the cause of the sexual differentiation of the organism, 

 the sexual differentiation of the organism is the cause of the 

 union of the germ-cells. 



(2) The present view differs, moreover, from that in which 

 the differences of sex are considered due to those differences 

 existing between the anastate and katastate of the protoplasm. 

 Instead of recognizing predominant katabolism as the male char- 

 acteristic and predominant anabolism as the female character- 

 istic, maleness and femaleness are considered to be due to two 

 different kinds of katabolism or irritability of the protoplasm. 

 For irritability of protoplasm is nothing more than the internal 

 explosion of its higher complex substance into simpler and more 

 stable substances, and this process of explosive change is what 

 we understand as destructive metabolism or katabolism. Ac- 

 cording to the present view, it is the nature of the direction 

 along which the katabolic changes of the protoplasm take place, 

 and not the difference exemplified in the alternating phases of 

 the protoplasmic changes, as anabolism and katabolism, that lies 

 at the bottom of the phenomena of sex-differentiation. . 



(3) The remarkable phenomenon of the "action at a distance" 

 between the two sexual cells observed by several naturalists, 

 which HasckeP has recently ascribed to the existence of what 

 he calls '' erotischer Chemotropisimis'' must be considered as the 

 repetition of the same phenomenon of irritability. In this case, 

 it may be considered that each sexual cell acts as a stimulus 

 to the other, owing to the difference of constitution which 

 they temporarily assume. By the time the close approxima- 

 tion of their essential sexual substance is accomplished, the 

 difference between the sperm-nucleus and the egg-nucleus com- 

 pletely disappears, and one morphological element — the seg- 

 mentation nucleus — which cannot be called either male or 

 female is the result. Maupas' conclusion ^ that '' La feconda- 

 Hon, €71 dernibre analyse, est nn phe'nomtne distinct et independent 

 de la sextcalite','' is highly instructive in this connection, if we 



^ Hgeckel, Anthropo^enie, 4th edition, 1891, Leipzig. 



2 Maupas, Le rejeunissement karyogamique chez les Cilies, Arch, de zool. exp. et 

 gen, T. VII, 1889, p. 479. 



