Mot tier. — Development of the Spermatozoid in Char a. 249 
for a vacuole. Fig. 1 seems to be the same stage as represented by 
BelajefFs Fig. 12. Fig. 3 is a median longitudinal section of a cell in 
the same stage as Fig. 1, but passing through the region between the 
ends of the thread, or on a line in the plane of ab , Fig. 1. The cytoplasm 
on the side opposite the nucleus, or that which will become the concave 
side of the mature sperm, is somewhat concave at this time, becoming 
much more so in a later stage. I observed nothing to correspond with 
Belajeff’s Fig. 15 a. In the stage of Fig. 1 no trace of cilia was seen. 
At this stage the chromatin is disposed in a hollow spirem with numerous 
interruptions, i. e. places free from chromatin but continuous as to linin. 
The chromatin is in the form of larger or smaller lumps or pieces. 
A little later in the development, the blepharoplast is more distinctly 
differentiated (Figs. 4, 5). It has become longer, and extends almost 
entirely around the cell. The anterior end is thinner and narrower than 
the posterior. In Fig. 5 it seems that the posterior end broadens rather 
abruptly. In this instance it seems that the thread, by shrinkage, has 
become separated from the nucleus at its point of contact. As a rule, the 
condition of things is as shown in Figs. 4 and 6, in which case the thread 
lies in such close contact with the nuclear membrane that it is not definitely 
distinguished there. This gives the impression that the thread consists of 
two separate pieces growing in opposite directions from a point or points 
on the nucleus as described by Belajeff. The two ends of the blepharo- 
plast rarely lie in the same plane at this stage. In the stage of Fig. 6, the 
cilia are present and of considerable length. In all cases in which their 
point of origin could be made out with certainty, that was always some 
distance from the anterior end. In no case were they found attached at the 
extremity, as figured by Belajeff in his Fig. 11. 
At this stage the entire protoplast has become more contracted. The 
diameter of the nucleus is also shorter, but the difference between that in 
Fig. 1 and in Fig 4 is due in some measure to a difference in the size of 
the cells. The surface of the cytoplasm at the point between the ends 
of the blepharoplast now begins to become concave (Figs. 6, 8), although 
this substance assumes, at a later stage, the form of a rounded vesicle 
(Figs. 9-13). A marked change is also manifested by the nucleus. It loses 
its spherical or elliptical shape, becoming denser and flattened on one side 
(Fig. 8), and assuming the form of a half moon or crescent. In structure 
it is dense and uniform. Both posterior and anterior ends of the blepharo- 
plast have become longer and thicker, projecting much beyond the cyto- 
plasmic mass of the cell. At a later stage (Figs. 11 and 12) the nucleus 
increases in length, becoming sausage-shaped, and makes about one 
complete turn in a spiral. In Fig. 13, the body of the sperm makes about 
three turns, the anterior end describing sharper curves than the posterior 
end. The cytoplasm of the cell now consists of a finely granular mass 
