DENDROCOMETES PARADOXUS. 351 



we may use the word "solution'' to express this meaning; 

 but we have no evidence that it is either of these pi'ocesses 

 that actually takes place. All the information we have is 

 that at a certain stage in conjugation certain structures, which 

 by their form and reactions to certain staius we recognise to 

 be meganucleoplasm, become indistinguishable from ordinary 

 living cytoplasm. There is evidence of a certain change in 

 chemical constitution, and perhaps this is only a very slight 

 change, and there is evidence of a certain change in con- 

 sistency. There is really no evidence that any substance 

 actually dies. Theoretically, there is no inconsistency in the 

 view that after the disappearance of the old meganucleus, its 

 nucleoplasm is still living in a modified form diffused through 

 the cytoplasm. The new meganucleus of the Dendrocometes 

 individual is an enlarged and modified nucleus derived from 

 one of the four micronuclei which are produced by the second 

 division of the segmentation nucleus, as described above, or, 

 to put the matter in few words, the meganucleus is derived 

 from a micronucleus. The important changes which occur 

 during the transition from a structure we call a micronucleus 

 to a structure we call a meganucleus are these : — 1st. A con- 

 siderable increase in size (from 4 ju in diameter to over 12 /i in 

 diameter in Dendrocometes). 2nd. A considerable increase 

 in the amount of chromatin. From whence is this increase 

 in substance derived ? It must come either directly as 

 formed nucleoplasm, or indirectly as food material from 

 which nucleoplasm can be formed, from the surrounding 

 cytoplasm. The evidence as to which of these two alterna- 

 tives is correct is not conclusive, but there is no sign of such 

 metabolic activity as might be expected if the material brought 

 to the new meganucleus is unformed food material, and con- 

 sequently it is very probable that the increase in size is due 

 to formed nucleoplasm transfused from the cytoplasm to the 

 new meganucleus. If this is the case, then the phenomenon 

 of the conjugation of the meganuclei I'eceives an explanation. 

 This view appears to me to receive considerable support 

 from the observation made by Biitschli that the posterior 



