THE CALCIFEROUS GLANDS OF EARTHWORMS 
469 
gland follicles, the follicular cavities being the spaces between a number of lamellae 
which are placed perpendicular to the axis of the oesophagus”; each follicle occupies 
the interval between the epithelial layer and the muscular coat. The lamellae 
consist of a double layer of cells, with vessels and connective tissue in their centre. 
These vessels are radially-directed branches of a series of longitudinal vessels in 
the thickness of the wall, and empty themselves peripherally into the vessels of 
the outer layer of the oesophagus. At first it was thought that the follicle could 
discharge the secretion into the oesophageal lumen by the separation of the epi- 
thelial cells of the oesophageal lining, but this appears not to be the case ; “ an 
gelungenen Durchschnitten finde ich einzelne Spalten des Epithels, welche die 
Miindungen der Follikel offenbar darstellen. Ob aber jeder Plattenfollikel eine 
einzige sol'che Mundung oder deren mehrere besitzt, ist nicht ausgemacht.” 
Perrier (19) gives an abstract of Claparede’s account, but in saying “ ces 
feuillets sont places entre la couche vasculaire et les couches musculeuses de la 
paroi oesophagienne,” he gets further from the mark than his original. 
Beddard, in his Monograph (l), does not give a separate description, but after 
giving a general account of the glands in their other and less complicated forms, 
adds that in Lumbricus only the most anterior gland on each side opens into the 
oesophagus, the hinder glands opening into each other and into the first pair. 
The textbooks, even when treating Lumbricus in detail as a type for study, are 
scanty or sometimes misleading. Vogt and Yung mention three pairs of thicken- 
ings, symmetrically situated in segments xi and xii — follicular glands intercalated 
between the vascular and muscular layers of the oesophageal wall, supplied with 
numerous blood-vessels. Marshall and Hurst were apparently the first to give the 
situation of the glands correctly ; the oesophageal pouches are a pair of short lateral 
diverticula of the oesophagus in segment x ; the oesophageal glands are two pairs of 
lateral protuberances on the sides of the oesophagus in segments xi and xii ; they are 
hollow, and their cavities, which are subdivided by a large number of horizontal 
lamellae, contain a milky calcareous fluid ; they are local thickenings of the glandular 
walls of the oesophagus, and their numerous cavities open into the oesophageal 
pouches. Sedgwick mentions the name, but nothing more. Parker and Haswell 
present a paraphrase of Marshall and Hurst, adding that the milky appearance 
of the fluid is due to its containing numerous particles of carbonate of lime. 
Shipley and MacBride are short, and not quite accurate ; the oesophagus “ has 
three pairs of lateral pouches developed on its walls. These pouches secrete 
calcareous particles, and hence are termed calciferous glands.” We do not think 
that a student would arrive at an adequate conception of the glands from any of 
these, descriptions. 
We have previously given the outstanding points in the conceptions of the more 
recent writers, and shall criticise these more in detail after describing the glands 
themselves. 
