BYE C. H. MARTIN. 
in her recent account of conjugation in Paramecium. In this 
case probably the new macronucleus would have resulted 
from the fusion of these two bodies, the new micronucleus 
being probably covered by some part of the old macro- 
nucleus. 
I can find no evidence in my preparations in support of 
Hickson’s view that the feeble-staining capacity of the deve- 
loping macronucleus is due to the fact that “at this stage 
either the whole or the greater part of the chromatin in its 
modified form passes into the surrounding cytoplasm, leaving 
the new meganucleus perfectly clear and homogeneous” (p. 
345), a process which Hickson compares to the extrusion of 
chromatin in the egg cells of some Metazoa. I am more 
inclined to believe that this primary loss of staining power 
on the part of the developing macronucleus is to be explained 
by a simple increase of size, which is compensated for at a 
later stage by the absorption of the chromatin from the 
remains of the old macronucleus. 
The final stage in the reformation of the nuclei is shown 
in Pl. VII, fig. 8.. This pair of conjugants was examined at 
intervals from 10.45 p.m. on August 31st to 8.10 p.m. on 
September 2nd. Unfortunately, nothing could be made of 
the micronuclear changes in the living animal. During the 
last five hours the tentacles, which had been previously 
shortened, commenced to elongate, and when the individuals 
were killed they had almost reached their normal length. 
From other observations on living material I am led to 
believe that the tentacles are not usually withdrawn during 
the early period of conjugation up to the stage F or G; 
during the much longer period associated with the final 
disappearance of the old macronucleus and the development 
of the new one the tentacles may become much shortened, 
and only attain their normal length after the reconstruction 
of the macronucleus, and shortly before the separation of the 
conjugants. 
In the final stage the macronucleus has a very characteristic 
appearance of a lightly-staining loose mesh, with scattered 
