Wilson . — Spermatogenesis in the Bryophyta . 435 
at this stage a row of three bodies is found lying within the nuclear 
membrane (Fig. 54). After a time the two bodies formed by constriction 
become free and pass into the cytoplasm, but do not take up definite 
positions (Figs. 55 and 56). While these bodies are being cut off, changes 
take place in connexion with the blepharoplast. A thread-like structure is 
produced in contact with it, which elongates and passes over the inner 
contour of the cell membrane (Figs. 53-5). The remarks made with 
regard to the origin of the similar structure found in Mnium hornum apply 
equally in this case. It may, however, be concluded that the process of 
formation is identical in the two plants. The growth of the thread con- 
tinues until it extends round about half the circumference of the cell 
(Fig. 54). Soon after this length has been attained the nucleus, which up 
to this stage has occupied a central position in the spermatid, passes towards 
the periphery and comes into contact with the thread at some distance 
from the blepharoplast (Fig. 56). 
At the next stage observed two structures are found in the cytoplasm 
of the spermatid. One of these is clearly similar to the limosphere already 
described in Mnium hornum. It consists of a comparatively large hollow 
sphere which takes up the nuclear stain freely (Fig. 57). In A trichum no 
obvious vacuole is found associated with the limosphere, the interior being 
filled with cytoplasm, or at least with a substance closely resembling it in 
structure and staining properties. Although this body often exists as 
a complete sphere, it frequently happens that only a segment of a sphere 
is present (Fig. 58). There can be no doubt as to its real form, as in all 
cases the limosphere in optical section is seen as a complete or interrupted 
ring from whatever direction it is examined. In Figs. 57 and 58 two 
spermatids are shown in planes perpendicular to each other, and it will be 
observed that in each the limosphere takes the ring-like form. 
No direct evidence as to the origin of the limosphere could be dis- 
covered, but it seems highly probable that it arises from one of the two 
bodies derived from the nucleolus. It is usually found occupying a position 
not far from the nucleus and close to the periphery of the spermatid. On 
the opposite side of the cell a second structure is present, staining similarly 
to the limosphere but of a different form (Figs. 57 and 58). This is similar 
in shape and appearance to the bodies previously cut off from the nucleus, 
and there is little doubt that while one of these produces the limosphere 
the other persists in an unaltered form. It must be left to future investiga- 
tion to determine whether this second body is equivalent to the ‘ Neben- 
korper ’ described by Ikeno ( 32 ) in Marchantia. This in future will be 
referred to as the accessory body. The nucleus now begins to elongate 
along the course of the thread, and soon reaches the blepharoplast, which 
in future retains its position at its anterior end. The nucleolus, which up 
to this time has been distinguishable, now disappears, and the structure of 
