THE SPINNING ORGANS. Al 
in diameter (about one-twelfth of an inch), lying close to the bases of the 
spinnerets. (Fig 30, py.g.) In form the individual glands are long, oval, 
pear shaped vessels, 0.22 mm. long, or, expressed approximately in linear 
measure, say one hundred and fifteen of average length would make an 
inch. In Argiope I find the average length about one eighty-fifth of an 
inch. At the inferior end they diminish grad- 
ually, passing into a duct which narrows towards 
the point of discharge, and which, together with 
a compact bundle of similar ducts, enters the 
interior of the spinneret, each one to discharge 
through its appropriate separate spinning tube. 
The wall of the gland contains a single cell stra- 
tum of a diameter of from 0.020 mm. to 0.024 
mm, These cells contain a quantity of small 
drops, which consist of a strong refractory sub- 
stance that agrees in appearance with the spin- 
ning material within the ducts. This glandular 
wall inclgses a large middle cavity, which is entirely filled with a viscous 
liquid spinning substance. The duct which projects from this 
gland possesses at the beginning a diameter of 0.024 mm.; nar- 
rows very soon after exit from the gland to the diameter of 
0.01 to 0.012 mm. That is to say, the termination of the duct is about 
one twenty-five-hundredth of 
an inch in diameter. At this 
width it runs unaltered to its 
place of exit from the spin- 
ning tube. 
These pyriform glands, as 
preserved in Argiope cophina- 
ria, while agreeing in 
general form vary a 
good deal in details, 
as shown by comparing the 
figures, 31, 32, and 33. Some 
of them are vermiform in 
¥ ant shape, Fig. 33, v; some are 
Fie. 34. View of the cylindrical glands, cy.g, and treeform 
glands, tr.g, of Epeira diademata. py.g, cluster of pyriform strictly pyriform, p; some are 
glands. d, bundle of ducts leading therefrom. spn, 4 spin- ¢ ‘ wag r 
neret into which the glands lead. (After Meckel.) cordate, Fig. 32, a and some 
Fic, 33. Pyriform silk glands. 
Pyriform 
Ducts. 
Argiope’s 
Glands. 
have long caudal parts, Fig. 
31, pe, which in general appearance resemble the cylindrical glands, but 
are on a much smaller scale. The vermiform glands contain a yellowish 
white substance. The other glands contain a somewhat similar material, 
but of a deeper yellowish color, and broken into distinct globules; while 
others contain a brownish liquid which has already been alluded to. This 
