PHARYNGEAL GLAND-CELLS OF EARTHWORMS. 
275 
specimens ; the large nucleolus, always present, may measure 
a third to two-fifths of the long, and even a half of the short 
diameter of the usually ovoid nucleus. Here too the cyto- 
plasm is not uniform, but shows darker and lighter patches, 
the latter sometimes almost clear and vacuole-like ; the darker 
patches are homogeneous, more or less central, and contiguous 
to the nucleus. 
Deeper in the pharyngeal mass (PL 19, fig. 9) the ad- 
mixture of cells is not great. The nucleus enlarges; the 
cell-body, smaller, dissolves at its periphery into a reticulum 
of fibrillar connective tissue ; or the cell-body may be absent 
as such, having wholly broken up into fibrils, so that one 
side of the nucleus is bare. Still nearer the pharyngeal 
epithelium the nucleolus decreases in size. 
The chief features of this stage are, therefore, the integrity 
of the cells in the lobular masses, where they have not begun 
to disintegrate ; and, apparently, the larger size of the 
nucleolus. The connective tissue change is proceeding in 
the cells which have penetrated inwards amongst the muscle 
fibres. 
Pheretima of diameter 1*5 mm. — The cells in the 
posterior and superficial portion of the mass measure 15-25 p, 
are of various shapes, and well defined in outline. The cell- 
body consists as before of two portions, a more lightly and a 
more deeply staining ; the latter occurring as amorphous 
masses, the former having a granular structure. The granules 
of the lighter portion appear to be the same in substance as 
the deeper staining masses, only not so closely aggregated; 
and the deeper staining portion merges into the other by 
becoming looser in texture. 
The passage forwards towards the pharyngeal epithelium 
is interesting. The cells, which posteriorly are in a compact 
mass with only an admixture of muscle strands, become 
much more scattered ; the muscle fibres, now arranged in a 
variously interwoven felt, contain within their meshwork 
isolated cells ; the whole texture is loose. In a few cells here 
and there the beginning of a connective tissue change is to 
