26 Life and Death, Heredity and Evolution 



(A to C), so that four are produced. Three of these dis- 

 appear, as did the old active nucleus, and the fourth divides 

 into two halves (D). One of these halves passes over into 



Figure 8. Diagram of the internal processes in the conjugation of 

 Paramecium caudatum; successive stages, ma., Macronucleus; mi., 

 Micronucleus. The striated and spindle-shaped bodies are the micro- 

 nucleus in the process of division. In D the three smaller dotted clouds 

 are three degenerating micronuclei. 



the other individual, with which mating is occurring (Figure 

 8, E), where it unites with the corresponding remaining half 

 of the reserve nucleus of that individual (F, G). That is, 

 the two conjugating animals exchange halves of their reserve 



