DEGENERATE SEXUAL REPRODUCTION. 



171 



genetic ovum has this and keeps it. The ordinary ovum lias it too, but extrudes 

 it, to get it back again from another source. If this is all the sperm does, one 

 can not help wondering that such a circuitous process could ever arise. 'The 

 entrance of the sperm must be looked at in two ways, — (a) it bears with it 

 certain hereditary characteristics, doubtless in the nucleus for the most part ; (b) 

 it brings with it a stimulus to division of a qualitative character, doubtless in some 

 part in its small cell-substance. The last function — the dynamic function — 

 Weismann wholly denies. The sperm has to him only a quantitative function. 

 Vet in spite of this virtual denial of sex, — that is, of any deep difference 

 between male and female whether, elements or organisms,— - he does admit a 

 qualitative action after all, for it is out of the mingling of the male and female 

 germ-plasma that all variations arise. 



4. Boveri makes an interesting note in regard to Weismann's discovery and 

 theory. There is a tendency, illustrated in ascarids, for the second polar 

 division to limit itself to the chromatin elements, to be a nuclear division rather 

 than a genuine cell-budding. Such a second division may possibly occur in the 

 parthenogenetic ova, while there may be in reality one extrusion. A second 

 nucleus may be formed, and retained, and act the part of a spermatozoon, very 

 much as Minot's theory supposes. 



(£■) Our theory of parthenogenesis is not so subtle as Weismann's 

 nor so simple as Minot's. Just as the spores which illustrate the 

 beginnings of sex may sometimes dispense with conjugation and ger- 



( disease (D). 

 Female < sex (s). 



(parthenogenesis (p). 



( parthenogenesis (p). 

 Male •< sex (s). 



( disease (d). 



Fig. 50. — Diagram illustrating the theory of parthenogenesis. 



minate independently, so may ova develop parthenogenetically. 

 These are to be regarded as incompletely differentiated female cells, 

 which retain a measure of katabolic (relatively male) products, and 

 thus do not need fertilization. Such a successful balance between 

 anabolism and katabolism is indeed the ideal of all organic life. That 

 the extrusion of one polar globule still occurs, only shows that some 

 katabolic products are still expelled. In parasitic fungi, sexual 

 reproduction disappears, and surrounding waste products presumably 

 help the purpose otherwise effected by sexual organs, so peculiarities 

 in the condition of parthenogenetic ova may explain the retention of 



