and of other related Primula Hybrids. 363 
remaining homogeneous, and do not display any inherent longitudinal 
fission until the chromosomes are about to proceed to the poles. 
This tendency of the longitudinal halves of the univalent chromosomes 
to adhere to one another is also characteristic of the heterotype divisions, 
for in the early hollow spireme stage the univalent strands are homogeneous, 
and it is scarcely ever possible to detect any longitudinal fission in their 
substance. 
During the somatic prophases the nucleolus buds constantly. This 
budding is carried on to a still greater extent during the heterotype pro- 
phase. 
Meiotic Phase of P. floribunda. 
There is a long-drawn-out rest between the last premeiotic and the 
prophase of the first meiotic division. At the last premeiotic telophase the 
whole chromosome breaks up transversely into rounded portions (Fig. 1). 
During the rest, these granules for the most part disappear ; perhaps they 
are absorbed by the large nucleolus. The nucleolus occupies the centre of 
the nucleus and usually stains very deeply, but sometimes appears as 
a plasmosome. The nucleolus, whether it be chromatic or not in staining 
reaction, buds freely (Figs. 7 and 8 ). Apparently it acts as the store-house 
for chromatin, which it deburses by exuding droplets of its substance into 
the nuclear cavity. The small buds whilst still attached to the nucleolus 
are more faintly staining, but as they separate they become chromatic and 
take a very bright stain, and pass to the periphery of the nucleus. Very 
delicate connexions join these round chromatic bodies to one another and 
individual bodies to the nucleolus. When the bodies arrive at the peri- 
phery they break up into smaller granules which as a rule stain less 
brightly. These bodies might be considered as representing prochromo- 
somes, but without doubt they are derived from the nucleolus, and they 
are irregular in size, in number, and in shape. The cytoplasm round the 
nucleus, at this stage, is very dense. 
A precisely similar resting stage has been described by Gates ( 15 ) and 
by Davis ( 5 ) in the Oenotheras. 
As the nucleolus continues to bud, the chromatin in the nucleus shows 
a decided increase, and this is accompanied by growth of the nucleus 
(Fig- 9), which may be said now to have entered upon the prophase. At 
the same time the fine connexions form more definite strands (Fig. 10), and 
the rounded beads of chromatin arrange themselves on the threads (Fig. 11). 
Sometimes several beads amalgamate to form an irregular mass, the earliest 
indication of the preparation for the coming synapsis (Fig. 12). In places 
the linin threads, bearing the chromatin beads, are seen to run parallel to 
one another and sometimes to join (Figs. 10, 11, 12). 
It is impossible to determine the significance of the parallel threads 
