388 



THE INFUSORIA 



FIG. 37. 



Diagram to illustrate the nuclear phenomena of the Ciliata, from the " Traite de Zoolog e 

 Concrete," based on the researches of Maupas. I, two individuals at the commencement of 

 conjugation, showing a single large meganucleus and a single small micronucleus. II, stage in 

 which the micronuclei have begun their mitosis. Ill, stage at the close of the first mitosis of 

 the micronuclei. IV, stage at the close of the second mitosis of the micronuclei. V, stage in 

 which there are four nuclei formed by the division of the micronucleus, and the meganucleus 

 is becoming irregular in outline. VI, stage in which three nuclei are undergoing degenerative 

 changes, and one the sexual nucleus is again dividing. VII, stage in which the sexual 

 nucleus has divided into a migratory and a stationary nucleus, and the migratory nucleus of 

 each individual has crossed into the cytoplasm of the other. VIII, stage in which the stationary 

 and migratory nuclei have come in contact with each other. IX, stage in which the cleavage 

 nucleus has been formed by the fusion of the migratory and stationary nuclei. The meganuclei 

 have now broken up into a number of small fragments. X, stage in which the individuals 

 have separated and the cleavage nucleus is undergoing its first mitosis. XI, the fragments 

 of the old meganuclei have entirely disappeared, and a new meganucleus and a new micro- 

 nucleus are forming from the daughter nuclei of the cleavage nucleus. XII, final stage with 

 a full-sized meganucleus and a micronucleus. 



