549 
Trow . — On Fertilization in the Saprolegnieae. 
side by side in the same Petri dish, apparently exactly alike, fixed 
simultaneously with chromacetic acid of the usual strength, and subsequently 
treated alike in every respect, yielded different results. One yielded me my 
finest preparations, the other provided only moderately good material. 
Sections 7-5 j u, thick are sufficiently thin to show nearly all the details 
perfectly, but I have relied entirely on sections 5 /x thick for the work 
described below. Sections which are thinner than this are more difficult to 
work with and there is as a rule no special advantage to be gained by 
their use. 
Most of the nuclear stains give good results, but gentian-violet is 
undoubtedly the best for general work. This was used, according to 
Gram’s method, with or without a second stain such as eosin. Very fine 
preparations were obtained with both gentian-violet and fuchsin when 
differentiation was carried out by chromic acid or picric acid solutions. 
Flemming’s triple stain proved to be an excellent one for most purposes, 
but was less constant in its action than the others. Haematoxylin stains 
are the least suitable, for the microsomata in the protoplasm— -the vibrioid 
organoids of Swingle (’98) — take the stain so greedily as to unduly mask 
the nuclear structures. With sections 1 /x thick, however, this stain would 
be the most satisfactory of all. The demonstration of critical and difficult 
points of structure may be carried out with any one of these stains, 
provided the material has been properly selected and prepared. 
Note on Nomenclature. 
The synonymy of the two species of Achlya with which we are 
concerned is somewhat confusing, both species having received the same 
name, Achlya polyandra. Humphrey (’92) recognized the confusion when 
preparing his monograph on the group and cleared up the difficulty satis- 
factorily. Fischer’s (’92) view is in practical agreement with that of 
Humphrey, although he left the synonymy in its original confusion. I have 
only to add that I accept the conclusions of the American monographer. 
It will suffice to point out here that the first species examined by me should 
be named Achlya polyandra , Hildebrand ; it is Achlya gracilipes, De Bary. 
The second species should be named Achlya De Bary ana , Humphrey ; it 
is Achlya polyandra, De Bary. 
Observations on Achlya polyandra , Hildebrand. 
The examination of this species occupied about eighteen months and 
many interesting facts came to light in addition to those with which we are 
at present concerned. I shall restrict myself to indicating the evidence 
procured as to the occurrence of fertilization, and such cytological 
phenomena as are associated therewith. Observations on the living 
