THE FUSION OF VENTRAL CANAL CELL AND EGG 229 
small and could not bring about the facts which have been observed. Figures 
I and 2 show the exact amount of plasmolysis due to killing and fixing. 
Furthermore, I am unable to believe that the technique employed 
is responsible for the fusions. Using the same methods described in this 
paper I killed at various times in the fall of 191 3 large amounts of Sphagnum 
for a study of the development of the archegonium. In no cases could be 
found the slightest trace of injury to the sex organ at any stage of its de- 
velopment. No canal cells were ever observed in the venter, and only after 
the disintegration of the canal row did any of the contents of the neck begin 
to make their appearance in the venter. At a later time this disintegrated 
matter fills the venter with a slimy mucilaginous mass which makes the 
study of fertilization extremely difficult. 
Still more important evidence that the technique is not responsible for 
the facts is that it is possible to demonstrate stages in the fusion of the proto- 
plasts and the nuclei. Not only that, but on a slide from a single head 
appear archegonia showing the following conditions: (i) Protoplasts of the 
ventral canal cell and the egg not in contact. (2) Protoplasts have fused, 
but nuclei, while in contact, are still separate and distinct. (3) Protoplasts 
and nuclei have fused completely. 
It seems hardly reasonable to believe that the technique could bring 
about the appearance of these varying stages in a single head. 
Insofar as the writer is aware, the archegonium of Sphagnum is unique 
among the Musci in that it comes to maturity in the late fall, withstands 
the severity of winter, and the egg is fertilized in the early spring. It under- 
goes great changes in temperature in the alternate freezing and thawing of 
certain winters; and when snow is absent and the temperature is low it is 
subject not only to freezing, but no doubt to considerable drying as well. 
It may be that these severe external conditions furnish the stimulus which 
brings about the fusion of the protoplasts. 
As yet I am unable to make any statement in regard to the behavior 
of the fusion nucleus. Whether it may develop directly into a sporophyte, 
whether or not it is capable of being fertilized, and whether or not this 
fusion is peculiar only to the species here studied — all these questions must 
await further work. 
Summary 
1. The ventral canal cell of Sphagnum suhsecundum is regularly per- 
sistent, and variable in size. 
2. The protoplasts of ventral canal cell and egg round off and, the 
wall between the two disintegrating, they lie near together in the venter of 
the archegonium. 
3. In material killed in the latter part of December a number of cases of 
the fusion of these protoplasts have been found. 
4. The fusion of the protoplasts is followed by the fusion of the nuclei. 
5. Undoubted cases of the degeneration of the ventral canal cell have 
also been found. 
