453 
Mnium affine, var. ciliaris ( Grev .), C.M, 
is due to the fact that the cilia are extremely delicate and, until the sperm 
becomes free, are usually wrapped very closely around and parallel with the 
main body. Figs. 28, 39, and 30, however, show very clearly that the 
cilia are attached at the extremity of the anterior end of the sperm. I use 
the term ‘ anterior ’ to refer to that extremity of the sperm corresponding to 
the portion or region in which the blepharoplast begins to develop. As 
shown in Fig. 30, the mature sperm of Mnium affine , var. ciliaris , seems 
to be essentially the same as that described for other Liverworts and 
Mosses. The vesicle which has frequently been described is readily found 
in slightly earlier or younger stages (Figs. 27 and 28). 
Summary. 
Resting stages of the spermatogenous tissue of Mnium affine var. ciliaris 
show the usual disposition of chromatin and cytoplasm. There is a very 
prominent, densely staining nucleolus, separated from a surrounding chro¬ 
matin network by a clear area. The cytoplasm may be evenly and smoothly 
granular or slightly flocculent. 
As the nucleus enters the prophase of division, the nucleolus stains 
more faintly, while immediately outside of the surrounding clear region the 
chromatin aggregates more densely. A coarse reticulum is formed which 
passes over into a clearly defined spireme. From the latter six chromo¬ 
somes are differentiated. 
So far as observed, the nuclear division proceeds in the usual manner 
without the accompaniment of polar bodies or plates. 
The cell-plate seems to be formed in the usual way through cyto¬ 
plasmic activity in the equatorial region of the spindle, and the daughter- 
nuclei are reorganized by passing through stages corresponding to those of 
the prophase, but in the reverse order. 
No diagonal division was found to occur in either Mnium or Poly¬ 
trichum. This makes it rather difficult to identify the last division of the 
spermatogenous tissue until it is completed. 
The first indications that this division is completed and that the 
androcytes have been formed is found in the separation and rounding 
off from each other of the cells. Next, the blepharoplast appears in the 
cytoplasm apparently as a cytoplasmic differentiation in the androcyte 
in which it functions. 
The blepharoplast develops as a more or less radially flattened band in 
a course closely applied to the plasma membrane. The nucleus becomes 
closely applied to the blepharoplast, loses its coarse network and stains 
homogeneously, and lengthens parallel with and very closely applied to the 
blepharoplast. The development of the blepharoplast precedes that of 
the nucleus. The nucleus and cytoplasm during this process may not 
