PROSTATE GLANDS OF THE EARTHWORMS OF THE FAMILY MEGASCOLECID2E. 449 
(a) Bottle-shaped cells, fairly short, compared with the elongated cells jnst 
described, debouching into the lumen by a neck. These are in length equal to one- 
third the thickness of the glandular walls or less. They are blue in colour in hsema- 
toxylin and eosin preparations, the blue colour being due to a mass of deep blue 
staining granules ; indeed, the cells consist of these granules, as those described above 
consist of pinkish granules. No nucleus is discoverable. 
( b ) The necks of the long pink-staining cells, often appearing merely as streams 
of light pink granules making their way towards the lumen. 
(c) Similar long necks or streams of blue granules, belonging apparently to those 
cells, deep in the gland, the contents of which stain bluish. 
There is thus no separate epithelium lining the lumen. 
In places there is a layer of muscular fibres within the glandular wall, at about 
one-third of the thickness from the lumen. 
There is a thin connective tissue capsule in many places on the surface of the 
gland, with occasional flattened nuclei ; in this capsule muscle fibres and small blood- 
vessels may occur. Connective tissue strands may join and become continuous with 
the glandular mass. 
In an apparently more advanced condition there are for the most part no cell 
boundaries ; the general substance of the gland stains partly pinkish and partly 
bluish, is amorphous, and of varying texture. The most obvious constituent of the 
glandular mass is the very deeply staining granules, almost black in hmmatoxylin 
preparations ; these are very numerous, spherical, and comparatively large : the 
largest, which are relatively few, are 4 p in diameter, the smallest 1 p ; intermediate 
sizes of 2 to 2'5 p are commonest — one of 3 p is a fairly large one. These granules 
occur throughout the mass, in general irregularly scattered, but near the lumen in 
bands. The appearance is that of dense streams of granules collecting from all parts 
of the gland, and discharging into the lumen. After discharge the granules appear 
rapidly to melt away into a pinkish staining substance (eosin staining), which forms 
a coagulum in the lumen. 
The mass is (in this more advanced condition) extensively vacuolated, but less so 
in the neighbourhood of the lumen than elsewhere ; the vacuoles are sometimes 
almost empty, and sometimes contain numerous granules. Nuclei are not visible, 
and cannot be made out with certainty even with the oil immersion lens. Here and 
there a granule appears to be surrounded at some little distance by a spherical 
membrane, and so simulates a nucleolus within a spherical nucleus. 
(3) The Ducts ( Prostatic Ducts and Vasa Defer entia). 
On passing along the glandular tube to the duct, the gland becomes narrower. 
A few elongated, almost rodlike, nuclei appear in the layer nearest the lumen. 
Muscular fibres begin to surround the whole. 
The nuclei near the lumen become more numerous, and of an ovoid form ; strings 
