164 
Spermatogenesis in Ixodes 
the wall of which the endoplasm, with the contents of the more or less coiled 
nucleus, centrosome-body and mitochondria, protrudes as a cap-shaped boss. 
The plasma ejection begins with the formation of a protuberance from the endo¬ 
plasm (PL XI, fig. 20 a), at first conical, later increasing considerably (Figs. 20 6 
and c ); lastly it separates itself from the same plasma body and forms a tail¬ 
shaped appendix fastened to the external end of the nucleus (Figs. 206, 21-23). 
This end of the nucleus pushes itself entirely outside the cell, the curved 
internal end of the nucleus alone remaining in the plasma and in this way 
keeping up the connection with the original plasma and the tail-shaped part 
of it. This tail has originally a purely plasmatic character, being formed of 
an internal, granular, mitochondrial cord, covered by a quite thin hyaline 
plasma-layer (Figs. 21, 22) 1 . After a while this conformation alters: it now 
forms a hollow tube through which several deeply-staining filaments pass, and 
is attached to the now funnel-like end of the nucleus (Figs. 23, 24). From the 
bottom of the funnel a thin cord is stretched along the whole appendix. 
Lastly the whole tail shrinks and assumes the form of a knotted thread, 
which finally vanishes entirely (Fig. 24). This process thus forms a plasma 
ejection of the sort that has been observed very commonly in the spermato- 
genetic development. 
During this development of the nuclear appendix the cell plasma undergoes 
equally remarkable changes. The ectoplasma-vesicle, rounded at the beginning 
(Figs. 18, 19), grows in length, at first assuming a club-like and later a rod-like 
shape (Figs. 21, 22), and at the same time the centrosomal corpuscle—this 
name seems suitable for the centrosome with surrounding mitochondria— 
passes from the endoplasma to the ectoplasma, where it takes its position 
near the boundary between the two (Fig. 24). The endoplasma, which was 
formerly gathered together in a solid mass, spreads in an ever thinner layer 
over the rounded front end of the ectoplasma-rod leaving the centrosomal 
corpuscle at the point of the rod (PI. XI, fig. 24). 
The movements of the nucleus continue during these changes in the 
plasma: as the endoplasma still has its compact form, the nucleus is seen 
situated either at right angles to the plasma-rod or as a continuation of it 
(Figs. 22, 23). Later on, when the endoplasma has spread, the nucleus is 
situated on the surface of the plasma-rod (Figs. 24, 25, a, b) and begins finally 
to roll itself up at its anterior end (Fig. 26), but stretches out again along the 
side of the plasma-rod. At the same time the centrosomal corpuscle becomes 
conical in shape and assumes a position at the end of the plasma-rod in close 
contact with the end of the nucleus, as shown in Fig. 31, and in transverse 
section in Fig. 27. 
Behind this centrosomal cone there now appears along the centre of the 
plasma-rod a stainable central cord (Figs. 26, 30, 31), the origin and signifi- 
1 This can be specially shown by material fixed with Flemming’s liquid. On Carnoy-material 
the tail shows from the beginning a sort of skeleton-structure. Unfortunately I have got no 
commencing stage of the tail-formation in Flemming-material. 
