1903] GAMETOPHYTES AND EMBRYO OF TAXODIUM 23 
groups of archegonia which were separated by a few layers of 
prothallial cells. They were always situated at the tip of the 
prothallium, but sometimes faced to one side. 
In fig. 57 the initial cells of the archegonia are shown just 
before the cutting off of the neck cell. The nucleus is situated 
at the very tip of the cell and most of the protoplasm is collected 
around it. A very large vacuole occupies the greater part of 
the archegonium. In fig. 60 the neck cell is being cut off. The 
nuclei in the central initials are preparing to divide. Their 
nucleoli are fragmented, and although this nuclear division was 
not followed in detail, the indications are that it is essentially 
like that in which the ventral canal nucleus is cut off. Fig. 61 
Shows the neck divided once longitudinally. In fig. 62 the neck 
cells are densely filled with starch and the amount of protoplasm in 
the central cell has increased greatly, especially in the lower part. 
In the occurrence of a single large central vacuole in the arche- 
gonium Taxodium resembles the Cupresseae and differs from all 
other conifers so far studied. At this stage we first notice 
slightly denser areas in the protoplasm at each end. The upper 
lies very near the nucleus and is smaller than the lower, which 
occupies a central position in the accumulated basal protoplasm. 
The nucleus of the central cell at this stage is very like that of 
the prothallial cells around it. In fig. 68 there has already 
appeared around the archegonial group a distinct layer of sheath 
or jacket cells. At the basal end of the group the angles between 
the archegonia are filled by these jacket cells, which are at this 
point generally larger than on the sides. This jacket is a con- 
stant accompaniment of the archegonia in all gymnosperms with 
the exception of Welwitschia. Arnoldi (’00) reports that in 
Sequoia the layer is incomplete, only certain cells acquiring the 
distinctive characteristics of modified jacket cells. I have fre- 
quently found in Taxodium a cell within this sheath, which in its 
Poverty of contents was easily to be distinguished from its 
neighbors, and resembles closely the ordinary prothallial cells 
around it. By far the larger number of the cells directly adjoin- 
ing the archegonia, however, are modified in the usual way into 
the nourishing jacket cells. The nucleus of the central cell, at 
