Wilson . — Spermatogenesis in the Bryophyta 443 
At this period two other structures appear in the cytoplasm of the 
spermatid (Figs. 77 and 78). One of these consists of a deeply staining 
spherical body somewhat larger than the blepharoplast and usually occupying 
a position midway between the nucleus and the periphery of the cell. 
This possibly corresponds to the ‘ Nebenkorper ’ described by Ikeno (32) 
in Marchantia , and subsequently recognized in other plants by several 
investigators ; this in future will be referred to as the accessory body. In 
close proximity to this another structure is found staining similarly to the 
‘ Nebenkorper ’, but not so deeply. 
This often takes the form of a sphere in which a portion of the surface 
stains more deeply than the remainder (Fig. 77). It is of considerable size, 
being three or four times as large as the blepharoplast. In other cases it 
has the appearance of a short curved rod from whatever direction it is 
observed ; its real form must, therefore, here correspond to the segment ol 
a hollow sphere. Occasionally two such rods have been observed in optical 
section joined together and making an angle with each other (the lower 
spermatid shown in Fig. 78). On account of its similarity in form, this 
structure strongly recalls the limosphere already described in the Mosses. 
In Pellia , as in A trichum , the limosphere is not found in connexion with 
a vacuole. It is probable that the sphere just described is the earlier stage, 
and that the segment is derived from it by the disappearance of the more 
lightly staining portion. No statement as to the origin of the limosphere 
or the body accompanying it can be made at present. They have not been 
recognized with certainty at any later stage and probably soon disappear, 
taking no direct part in the formation of the spermatozoid. 
At this stage, when the spermatid is viewed from above or below, the 
nucleus is found to occupy the greater part of the cell, extending round 
about half the circumference. The blepharoplast is situated on the peri- 
phery a short distance from the nucleus and connected with it by the 
thread-like structure already described (Fig. 77). 
It is probable that the blepharoplast and the portion of the thread 
which projects beyond the nucleus together correspond to the ‘ Cytoplasma- 
hocker ’ described by Strasburger (62) in Pellia calycina . This investigator 
describes the ‘ Cytoplasmahocker ’ as a highly refractive, slightly elongated 
body occurring on the outer edge of the nucleus and bearing the two cilia. 
He gives no details as to its formation, but the resemblance of the structures 
in the two species suggests similarity of development in each. 
Up to this time a number of small irregular masses of chromatin can 
usually be distinguished, but the substance of the nucleus now becomes 
homogeneous. It begins to increase in length and at the same time 
decreases in width. The elongation proceeds in both directions along the 
course of the thread-like structure, and at the anterior end the blepharo- 
plast is soon reached : this body retains its position at the end of the 
