1897.] Embryology. 639 
It is subsequent changes in these nucleoli that constitute the remark- 
able, complex figures seen in the numerous illustrations. 
The part of the original nuclear filament not concerned in forming 
nucleoli becomes resolved into innumerable minute granules. These 
granules arise from the filament in various ways somewhat as do similar 
granules from the nucleoli, as described below. The granules disperse 
in the nuclear sap, but not without reference to the pre-existing 
structure of that sap, in fact they seem to travel out along the strands 
of the plasmatic network. Ultimately. these granules dissolve and the 
filament is henceforth represented only by the nucleoli. 
We come thus to a stage in which the nucleus contains no visible 
objects except the chromatic nucleoli and the fine plasma net. The 
nucleoli, as they formed from the filament, went out to the periphery 
of the nucleus to lie near its membrane. They next begin a migration 
inwards towards the central part of the nucleus and enlarging become. 
resolved into remarkable figures. These figures are different in succes- 
sive years and even in different animals and much of the labor of the 
authors has been the attempt to arrange the large mass of material in 
some classified order. 
These figures continue to be found all through the growth of the 
egg ; successive generations of nucleoli arise and are resolved into figures. 
Many of the figures would be taken for atrangements of chromatin 
directly arising from the original loop—others seems strange and 
bizarre. 
Any continuity of chromatin seems here out of question, except as 
the nucleoli first arise from chromatin and subsequently are continued 
as successive generations of chromatic figures; any attempt to trace 
continues chromatic bodies, chromosomes—seems most impossible. 
We cannot attempt in the limit of a short abstract to mention the 
numerous shapes the nucleoli assume in the process of resolution. 
Starting from the form of a spheroidal, apparently homogeneous body 
the nucleolus may swell up into a spongy mass that transforms into a 
large network of complex strands, each composed of innumerable gran- 
ules. Or the nucleolus may branch out into plume and brush-like 
figures, often resembling a test-tube-or lamp-chimney-cleaner. Other 
nuclei form branching trees, coiled filaments, groups of balls with 
ora connections, stars and M masses looking like spat- 
paint. 
Bowi of the figures are found only at certain periods of the year 
others in various stages of the development of the egg; some periods 
are characterized by the occurrence of only one form of figures while 
others have a prevailing form and others a mixture of many forms. 
