NUTRITION AND REPRODUCTION. 1 59 



that belonging to it as an individual, so that a part is thus 

 elevated into a (new) whole " (GenereUe Morphologie, vol. 

 ii. p. 16). The functions of growth and reproduction are 

 therefore very intimately connected. Reproduction is only 

 a continuation of the growth of the individual. But the 

 latter, again, depends in its compound form, on generation, 

 that is, on the multiplication of the simple constituent indi- 

 viduals. While, on the one hand, reproduction appears to 

 be only a growth of the individual to a size exceeding that 

 of the individual, — compound growth, on the other hand, 

 is the result of the reproduction of simple individuals of 

 the first order. This view enables us clearly to understand 

 rejDroduction and, consequently. Heredity, which otherwise 

 appears to be an obscure and mysterious process. 



To prove the correctness of this view, we must start 

 from the simplest form of reproduction, that is, division, as 

 it occurs in the case of almost every cell. When the cell, 



Fig. 16. — Blood-cells (corpuscles), increas- 

 ing by self-division, from the blood of the young 

 embryo of a stag. Each has originally a kernel 

 (nucleus), and is globular (a). When the cells 

 are about to multiply, the kernel first separates 

 into two {h, c, d). The protoplasmic body then 

 becomes pinched in between the two kernels, 

 which separate more and more from each 

 other (e). Finally the cell parts into two, at 

 the point where it was pinched in (/). (After 

 Frey.) 



having, by the absorption of nutrition, already reached its 

 usual size, exceeds that measure, it divides into two cells 

 (Fig, 16). Just in the same way in many-celled animals (for 

 example, Corals), when the individual grows beyond the 



