CHAPTER XVII. 



Theory of Reproduction. 



§ I. The Essential Fact in Reproduction. — In the foregoing 

 chapters, the facts involved in the different forms of repro- 

 duction have been analysed apart, and separately discussed. 

 Male and female organisms have been interpreted as relatively 

 katabolic and anabolic ; the origin of sex, in the individual 

 and in the race, has been traced back to the preponderance of 

 anabolic or katabolic conditions ; the ultimate sex -elements 

 were seen to exhibit the same contrast in its most concentrated 

 expression ; fertilisation was regarded as a katabolic stimulus to 

 an anabolic cell, and on the other side, of course, as an anabolic 

 renewal to a katabolic cell, as well as the union of opposed 

 hereditary characteristics. Only by a separation of the problem 

 of "sexual reproduction" into its component problems can the 

 solution be reached. Sexual reproduction is like a complex 

 musical chord in the organic life, combining several elements, all 

 of which, however, admit of the same fundamental analysis. 

 Two problems remain, — the psychical aspect of the process ; 

 and the import of that common feature of all reproduction, the 

 separation of part of the parent organism to start a fresh life. 

 The latter forms the subject of the present chapter. 



§ 2. Arginnent from the Beginnings of Reproduction. — 

 Leconte and others have pointed out that reproduction really 

 begins with the almost mechanical breakage of a unit mass of 

 living matter, which has grown too large for successful co-ordi- 

 nation. Reproduction, in fact, begins as rupture. Large cells 

 beginning to die, save their lives by sacrifice. Reproduction is 

 literally a life-saving against the approach of death. Whether it 

 be the almost random rupture of one of the more primitive 

 forms such as Schizoge?ies, or the overflow and separation of 

 multiple buds as in Arcella.^ or the dissolution of a few of the 

 infusorians, an organism, which is becoming exhausted, saves 

 itself, and multiplies in reproducing. In some cases, reproduc- 



