346 SYDNEY J. HIOKSON. 



appears to be no recovery in the amount of chromatin before 

 the next division occurs. In the history of the formation of 

 the new megauucleus of Dendrocometes, however numerous, 

 granules of chromatin subsequently appear at the periphery 

 (PI. 18, figs. 4, 7, 8), aud later they invade the clearer 

 central parts (PI. 18, figs. 5, 15), to build up the 

 characteristic chromatin network of the functional mega- 

 nucleus. The exact meaning of this elimination and recovery 

 of chromatin at this stage is a mystery, but taken in con- 

 junction with the other phenomena of conjugation, it may 

 be regarded as a part of the general process of protoplasmic 

 reconstitution of the organism, which is the essential feature 

 of the sexual act. 



General Considerations. 



Maupas, in his famous work on the conjugation of the 

 Infusoria, expressed the opinion that conjugation is essentially 

 an affair of the micronuclei ; and I think that the prevailing 

 opinion held by zoologists who have taken a special interest 

 in this matter, is in general agreement with this view. 

 Biitschli's opinion, as expressed in 'Infusoria' (p. 1643), is 

 that the meganucleus is of tlie nature of a somatic nucleus 

 (Gewebekerne), which becomes gradually exhausted (allmah- 

 lich abgenutzt wird) during somatic life, whilst the micro- 

 nucleus is of the nature of the sexual nuclei of Metazoa, and 

 does not become exhausted by the vital processes (keine 

 solche AbnutzLiug erfahrt). Wilson (26) expresses very 

 fairly the prevalent view in this sentence : " Daiing conjuga- 

 tion the macronucleus degenerates and disappears, and the 

 micronucleus alone is concerned in the essential part of the 

 process." 



With the general proposition that the meganucleus is of 

 the same essential nature as the nucleus of the somatic cells 

 of the Metazoa, and that the micronucleus is essentially a 

 sexual nucleus, I am in agreement ; but there are serious 

 objections to be raised to the further proposition, that the only 



