DENDROSOMA RADIANS, EHRENBERG. 
155 
50, 51, 52, which are drawn to the same scale. Fi". 50 
represents the terminal extremity of the megannclens in an 
arm, and the granules are of an average size. The diameter 
of the megannclens in this specimen was 2 ju, and the largest 
granules were approximately 0'85 /.t in diameter. Fig. 51 
represents a longitudinal section near the base of an arm in 
which there were two meganuclear bands nearly parallel with 
each other. The larger of these bands was about 3‘4 p in 
diameter. The granules in the.se bands are extremely small, 
but at intervals large lumps of chromatin, in some cases over 
4 fi in length, occur. Fig’. 52 represents a section through a 
remarkably swollen part of a megannclens (25’5/.t by 20’4 /<), in 
which many of the granules are very large; the largest are 
about 2 5 fi in diameter. The study of the variation in size 
and form of the granules in the meganucleus suggests a com- 
parison with the descriptions given of the megannclens in 
Carchesium and other Ciliate Infusoria. In Carchesium, 
accoi’ding to iMrs. Bidder (Greenwood, 14), there is a nuclear 
membrane which in certain stages is “ denionsti-able with 
difficulty”; the contents consist of granules of two kinds 
floating freely in the nucleochyme, and there is no indication 
of permanent linin threads connecting these granules togetlier. 
fl'he granules are of two kinds — the proto-macrosomes and 
the proto-mici’osomes, and of these the proto-macrosomes 
certainly and the proto-microsomes probably undergo 
changes in association with nutrition. The larger granules 
of the meganucleus of Dendrosoma seem to agree with the 
macro.somes of Carchesium, although we have not observed 
the vacuolated condition which the latter sometimes exhibit. 
A distinction between macrosomes and microsomes has not 
been demonstrated in Dendrosoma-, but it is possible that 
further investigation might yield similar results to those 
obtained in Carchesium. 'Ihis comparison suggests that 
the great difference we have recorded in the size of the 
granules of the meganucleus may be in some way associated 
with nutrition. 
Division of the mega nude us. — The only method of 
