STUDIES ON EARTHWORMS. L rr | 
Lumbricus; they are filled with the same large globular 
granules, but the nucleus, instead of being near the base of the 
cell, is sometimes in the centre of the cell, rarely so close to 
the base as in Lumbricus. Some of these cells seem to be 
emptied of their granules, leaving a network of protoplasm 
(fig. 40,5). Frequently a goblet cell appears to have more than 
one nucleus, but a faint line can generally be seen (a), and I 
take it that the goblet cells being very closely packed, a part of 
a neighbouring cell and nucleus is included in the section. 
The basement membrane is fairly thick (m.). 
The circular muscular layer (musc. circ.) is very much 
thicker compared to the epidermis than in Lumbricus, nor are 
the strands of muscle so closely packed nor so regularly circular 
as in that worm. In Microcheta some of this layer appears to 
be rather oblique, and the muscle-fibres to be grouped in strands, 
and separated more frequently by connective tissue than is the 
case with Lumbricus. Between the circular and the longitu- 
dinal layers of muscle is a fairly thick layer of connective 
tissue (ct.) 
The longitudinal muscles (mus./g.) present the chief 
point of difference between the structure of the body wall of 
Microcheta and of uumbricus. In the latter form there are 
groups of muscles, where the strands are arranged on each side 
of aradial piece of connective tissue, each group appearing more 
or less separate from the neighbouring group and thus having 
a bipinnate arrangement. But in Microcheta we have no such 
grouping. The muscle-strands are all packed together in 
connective tissue. The section of the strands is circular, or 
elliptical—not linear as in Lumbricus—and we have two or 
three strands grouped together and surrounded by connec- 
tive tissue; so that this layer, when the section is stained in 
Borax carmine, appears as a number of more deeply stained, 
more or less circular masses, each in a setting of connective 
tissue. A similar difference in the breaking up of the longi- 
tudinal muscular layer is found to obtain amongst various 
genera and subgenera of Sipunculid Gephyreans. 
The whole depth of this layer is very great, being five or six 
