630 Trow . — The Karyology of Saprolegnia . 
of being made up of a number of much smaller ones, or 
sometimes appear distinctly spongy, and one can therefore 
readily understand how an observer might be tempted to 
conclude that they are fusion-nuclei. I believe that the 
granulated and spongy appearances may be traced to the 
same cause — the expansion and breaking up of the spongy 
network of which the chromosome-mass consists. The appear- 
ances represented in Fig. 12 a are then to be regarded as due 
to nuclear degeneration and not to nuclear fusions. 
The protoplasm of the thin layer soon begins to be heaped 
up at certain points in order to constitute the oosphere- 
rudiments : Fig. 13 a , b, and c show an early stage in the 
development of these. In the three successive sections 
figured, three distinct rudiments will be noted. In each 
rudiment there is one typical nucleus and one only , having the 
structure we have observed in previous stages. Associated 
with it are degenerate nuclei, and some of these do really 
appear to unite in pairs: five distinct pairs may be noticed in 
the three sections. Not only do the forms assumed by these 
nuclei suggest fusion, but the increase in size and decrease in 
number is very marked. I believe that much of the confusion 
which has crept into the study of apocytial plants can be 
traced to the fusion of these degenerate nuclei, together with 
the study of badly stained preparations. These abnormal 
nuclei ultimately undergo complete degeneration, becoming 
more or less deformed, and finally losing all capacity for 
taking up nuclear stains. I have never been able to discover 
them in fully formed oospheres, but they are frequently 
still noticeable as irregular bodies near the surface of the 
older oosphere-rudiments. 
Fig. 14 shows one of four sections through a small oogonium 
28 [i in diameter, which contained four oosphere-rudiments, 
each uninucleate like that figured. The perfect agreement in 
structure of this nucleus with the typical ones seen in Fig. 13, 
and the complete dissimilarity from the degenerate nuclei, 
leave no room for doubt as to which are the functional nuclei 
in the younger oogonia. 
