286 J. B. GATENBY AND J. H. WOODGER 
plasmic vacuoles approach and fuse into fewer larger granules, 
which eventually all come together to form a single large 
granule lying in a single archoplasmic vacuole. This structure 
is known as the proacrosome. 
14. The Golgi apparatus complex now consists of numbers 
of dictyosomes lying on the surface of the archoplasm: the 
latter contains near its centre the proacrosome. ‘The latter 
soon becomes distinguishable into an inner darkly-staining 
bead surrounded by a paler cortical zone, the whole lying 
in the archoplasmic vacuole. 
15. The Golgi apparatus complex has moved up towards 
the anterior end of the spermatid nucleus, and it now becomes 
applied to the nuclear membrane. Where the complex touches 
the membrane the Golgi elements or dictyosomes are pushed 
aside, so that the archoplasm comes into direct contact with 
the spermatid nuclear membrane. 
_ 16. From its more or less central position the proacrosome 
passes through the archoplasm and becomes applied to the 
nuclear membrane, upon which it becomes flattened so as to 
form a hemisphere. The proacrosome is now spoken of as the 
acrosome: it has an inner zone, an outer zone, and it is still 
covered on its outer side by the archoplasmic vacuole. Where 
the latter comes into contact with the archoplasm there is 
differentiated the covering membrane of the acrosome, which is 
rarely very clear. 
17. The acrosome grows rapidly, and at a stage when it 
has differentiated to form a conspicuous cap at the anterior 
end of the spermatid nucleus, the Golgi elements with archo- 
plasmic remains, which hitherto covered and embraced the 
developing acrosome, gradually drift away and pass towards 
the posterior end of the spermatid. 
18. The acrosome now develops by itself. The lower part 
of the archoplasmic vacuole spreads down past the equator 
of the spermatid nucleus, and the lower edges of the outer zone 
of the acrosome cover the equatorial region of the nucleus. 
The archoplasmic vacuole becomes less evident. 
19. The outer zone of the acrosome grows very rapidly, 
