Life and Death, Heredity and Evolution 



There is no point to the male element's separating from 

 the female element, to immediately unite with another female 

 element, if the whole rationale of the process is merely to 

 bring maleness and femaleness together; they needed but 

 to remain where they were! 



From the fact that "male" and "female" of one individual 

 separate, and immediately unite with "female" and "male" 

 respectively of another individual, it might, seem that the 

 essential point is not the mere union of male and female, 

 but the union of parts of diverse individuals, and many 

 have held this to be the case. But here again we meet a 

 set of extraordinary facts which make this way of looking 

 at the matter as difficult as the other. In many organisms 

 the unions that occur are between half nuclei of the same 

 individual, or even of the same cell; this is the process that 

 is becoming familiar under the name autogamy. 



A typical striking case of this union of half nuclei from 

 the same cell is seen in the small parasitic flagellate in- 



Figure 41. Mating of two halves of the nucleus of same cell (auto- 

 gamy) in the cyst of Trichomastix. A, division of the nucleus; B, the 

 two nuclei separated by a large mass of reserve food matter; C, first 

 "reduction" division of each nucleus; D, second reduction division; E, 

 the two nuclei approach each other; F, they unite into one. After 

 Prowazek from Hartmann, 1909. 



