1903] GAMETOPHYTES AND EMBRYO OF TAXODIUM 1g 
that there is a great difference in structure in the two cases. 
Moreover, this tissue in the Abieteae is always spoken of as dis- 
organizing. Coulter and Chamberlain (’or) have an interesting 
paragraph on this subject. They say: “In our figure of a 
mother-cell of Pinus Laricio imbedded in nucellar tissue, it is 
apparent that it is surrounded by a rather definite zone of cells, 
two to four layers in depth, which give evidence of breaking 
down. After endosperm-formation is somewhat advanced, this 
interesting zone becomes differentiated into two distinct regions, 
an outer layer of tabular, almost empty, cells, and an inner region 
of polygonal cells with densely staining contents.” I do not 
know of any case, however, where this layer is said to persist in 
later stages. Strasburger (’79) describes a zone of more or less 
disorganized cells around the germinating megaspore of Thuja. 
I have examined growing sacs of Pinus, Larix, Thuja, Podocar- 
pus, and Taxus in reference to this” point. At the base of the 
prothallium in Podocarpus and around the very young germi- 
nating megaspore of Thuja there are cells which approach, in 
appearance, those found in Taxodium. In fact, there are fre- 
quently present around growing prothallia a number of swollen 
free cells, which might be compared to such a tissue as I have 
described in Taxodium, but in most cases these cells are not in 
close contact with one another and their development can be 
gradually traced from the ordinary cells of the nucellus. But I 
have not studied any of these plants carefully enough to deny 
the persistence in them of this tissue, and further observation is 
necessary to decide the matter. 
It is difficult to understand the constant occurrence of a defi- 
nite layer of large, distinctive, undisorganized cells around the 
§rowing prothallium in Taxodium, unless we ascribe to them an 
active part in the-nourishment of the young gametophyte, and 
this I believe to be their real function. If this interpretation is 
the correct one, the tissue in question may be considered as a 
tapetum, which, instead of disorganizing at the maturity of the 
Spore, as is usually the case, has continued its growth to keep 
Pace with the developing prothallium which it continues to 
Nourish until mature. If we consider the archesporium as 
