Trow . — On Fertilization in the Saprolegnieae . 551 
with its accompanying nucleus and be regarded as one body. In fact, it is 
extremely likely that during imperfect fixation of the nuclei and ‘ coenocen- 
trum 5 a fusion of these very distinct bodies actually takes place — a result, 
however, of no special significance so far as concerns the demonstration of 
the occurrence of fertilization. The nuclear membrane of the centrally 
placed nucleus of the ‘ origin ’ is very difficult to demonstrate. I frequently 
could not satisfy myself as to its presence at this stage. It is probable 
that the nuclear membranes of the nuclei of the oospheres make their 
appearance just at this point. 
The representation of a fertilization-tube in direct, open communica- 
tion with a young oospore in Fig. 11 is noteworthy. It might well be 
accepted as a positive proof of fertilization. It is, however, an anomaly ; 
the tubular neck has a relatively thick wall, a feature invariably absent 
from normal fertilization-tubes ; and the adjacent section, represented in 
Fig. 12, shows a fertilization-tube already attached to the oogonium and 
delimited from it in the usual manner by a definite transverse membrane. 
There can be little doubt that the normal fertilization was effected by the 
second of these tubes and that the first one, notwithstanding its clearness, 
is anomalous. It is the only one of this type seen, and yet hundreds, if not 
thousands, of fertilization-tubes have been examined in normal contact 
with the young oospores. Such an anomaly, though obviously patho- 
logical, or at any rate very exceptional, is however not without its 
significance. Special reference should be made to Fig. 13, showing 
a typical fertilization- tube in direct communication with the oosphere or 
oospore. In this case the staining was so dense that the nuclei could not 
be seen at all, but an area of protoplasm in the oosphere, just opposite to 
the fertilization-tube, was stained in exactly the same way as the protoplasm 
of the tube itself, and the direct continuity of the protoplasm of the two 
organs was, without difficulty, established. This preparation, though 
useless for the study of karyology, sufficed to settle the question as to the 
existence of an open communication between the fertilization-tube and the 
oosphere, and furnishes some evidence for the view that protoplasm passes 
over from the fertilization-tube to the oosphere. It is interesting to note 
the way in which the gameto-nuclei approach each other, as shown in 
Fig. 8. The nuclei are oval and possess deeply stained granules at the 
somewhat pointed anterior ends. These granules lie apparently inside the 
nuclear membrane. They are typical, not exceptional, structures in this 
species, at this stage of development — at any rate with the methods of 
preparation employed by me — and are probably to be connected with the 
existence of centrosome-like structures which have fused more or less com- 
pletely with the nucleus. However, the newer observations made on the 
second species — the details of nuclear structure being worked out more 
thoroughly in that case — will throw additional light on this phenomenon. 
