THE CALCIFEROUS GLANDS OF EARTHWORMS. 
483 
These latter expressions of the author’s views scarcely require criticism. With 
regard to the former — earthworms as aquatic animals — while some certainly can and 
do live in water or mud, and others in damp earth, a number even among the 
Lumbricidse can endure a considerable degree of dryness. According to Szuts (29), 
though Allobophora lives mostly in damp soil, it may be found under very various 
conditions ; Eiseniella is found in damp or swampy meadows ; Eisenia rosea may be 
found in luxuriant garden earth, and also in less nutritive loamy soil, or even between 
the stones of pavements in towns ; Lumbricus and Octolasium can live on high 
mountains, and in stony, sandy, siliceous or loamy earth. The idea of a current of 
water passing through the glands (even were there a definite opening at the hinder 
end) may be dismissed as fanciful. 
Summary and Conclusions. 
(1) The calciferous glands of earthworms were rightly interpreted by the older 
authors as foldings of the oesophageal epithelium. The simplest condition is that 
where there occur slight segmental bulgings of the canal, within which are a number 
of transverse folds of the epithelium. 
(2) In many forms the bulgings become diverticula, with wide or narrow mouth. 
The extreme form under this head may be seen in, for example, Octochsetus barkud- 
ensis, where the glands are large lobed sacs, in the interior of which are numerous 
thin lamellae extending nearly across the lumen ; the sacs communicate with the 
oesophageal canal only by a narrow neck or “duct.” 
(3) The condition in Eutyphceus may be considered to have arisen from the 
fusion, along their edges, of a series of parallel epithelial lamellae, transverse in 
direction, on each side of the oesophagus. The interlamellar spaces are here open 
above near the dorsal wall of the oesophagus, but are closed below by the ventral 
oesophageal wall. The glands here cause but little external swelling, being as it 
were withdrawn within the oesophageal wall. This is the end term of a type of 
evolution which starts with simple transverse lamellae. 
(4) The condition in the Lumbricidse originated in a series of longitudinal 
lamellae. The mode of evolution has been comparable to what has happened in 
Eutyphceus — the inner edges of the lamellae have fused. In this way a series of 
longitudinal tunnels has been formed, in and part of the epithelial coat of the 
oesophagus, and entirely within the muscular coat. These tunnels open in front, 
where the longitudinal folds begin, into the oesophageal pouches in segment x ; they 
become progressively smaller, and cease in xiv without posterior openings. 
(5) The epithelium of the glands is in all cases- continuous with that of the 
oesophagus, and comparative anatomy shows that the various forms of glands are 
essentially due to various forms and degrees of complexity of the epithelial folds. 
The glands are therefore not mesodermal in origin, and are not merely the walls of 
blood-vessels, as has recently been contended. 
