Dim Prof. Farmer, Messrs. Moore and Walker. [Apr. 11, 
the sphere, or at least some of them, enter into direct relation with parts of 
the spermatozoon which arises by further differentiation of the cell. As 
regards the archoplasm, with which we are more directly concerned, it is 
again seen to contain a number of minute vesicles which continue as before 
to grow in size, whilst each contains a single refractive and stainable granule 
(figs. 4, 5). Subsequently, several of these vesicles fuse together, so that at a 
later stage in the metamorphosis of the cell into a spermatozoon there only 
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Fig. 4. Archoplasm with centrosomes lying outside it in prophase of the first maiotic 
<livision in testis of mouse. 
Fig. 5. Spermatid of mouse, showing origin of vesicles in the archoplasm. 
remains a single large clear body, bounded by a distinct membrane, contain- 
ing in the centre one or more darkly staining granules (figs. 6, 7, 8). 
This body, originally described by one of us in 1895 as the archoplasmic 
vesicle,isa very conspicuous and apparently constant feature peculiar to the 
spermatogenetic cells of, at any rate, the vertebrata, and it has since been 
encountered beyond that group by other observers. 
When fully developed it often assumes a size approximating to that of 
the nucleus. Indeed, the latter is often deformed and made to assume a 
crescentic or cuplike shape owing to the enlargement of the adjacent archo- 

