42 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
difference in size and form is perhaps largely due to the presence in 
greater or less quantities of the liquid silk contained within the glands. 
The caudate extensions of the pyriform part manifestly permit the secre- 
tion and storage of larger quantities of spinning material. 
The Cylindrical glands, cy.g, have been considered by Meckel under two 
distinct forms, according as they have in one case an ampullate extension 
towards the duct, or in the other case are simply cylindrical 
Cylin- tubes. These forms he denominates Cylindrical and Ampullate. 
ion They appear, however, to be the same glands, exhibited under 
Glands. ~~.) “PPE i Paes ‘ 2 
different conditions; and eyen according to Meckel they have the 
same structure and discharge from the same character of spinning spigots. 
They appear to be, as Bucholz and Landois regard them, but one gland. 
The difference in their form is probably due to the same cause by which 
the somewhat similar difference in the form of pyriform glands has been 
explained, namely, the presence of more or less of the secreted spinning 
substance. The number of cylindrical glands is eight, four of which are 
located on each side of the body. 
These glands represent very long cylindrical tubes, which extend from 
the root of the spinnerets to the fore part of the body, near the breathing 
organs. Thence, bending with waving conyolutions, they return to their 
origin. If they were stretched out entire, their length would almost equal 
the length of the animal itself, of which, perhaps, they occupy only a third 
part. This extraordinarily long gland terminates with a double fold be- 
neath the lower end of the gland and the spinneret, which if stretched out 
straight would exceed the length of the whole gland section. On the walls 
of the gland is a simple stratum of gland cells, whose diameter is 0.020 
to 0.024 mm. They are precisely like the cells of the pyriform glands, 
and like them are filled with a great number of minute shining globules 
of spinning substance, 
In the direction of the duct, the tubular part of the gland enlarges 
greatly into an elliptical, ampullate extension, am, Fig. 35, from which the 
duct proceeds. The construction of this ampullate swelling is 
The Am- the same as that of the cylindrical section, and in fact the swell- 
cee aad ing may be caused simply by the accumulation of spinning 
: material in the lower part of the gland, which thus rounds out 
that part into an ampulle, am. 
The duct of the cylindrical gland, ¢.du, has at its origin a width of 
0.065 to 0.070 mm. (one three-hundred-and-fiftieth of an inch) and runs, 
quickly narrowing at first, to the root of the spinneret; thence 
it returns again, folded like a bent knee, k, and once more doub- 
ling (do.) and proceeding downward discharges through its appro- 
priate spinning spigot, a brown obtuse cone on which stands a clear trans- 
Cylindri- 
cal Duct. 
1 Meckel and Oeflinger both report six glands of this kind on either side. 
