INTRODUCTION. 
5 
canal, of moderate length, which dilates and adheres by its parietes to a kind of epiploon, 
filled with adipose granules, situated in the abdomen. Posteriorly the dilated part becomes 
stronger in texture, insensibly contracts, and then undergoes a second dilatation before it 
opens into the rectum. 
Spiders employ their falces to seize, kill, and retain the insects that they prey upon, and 
their maxillae to masticate them and to express their fluids, which, when mingled with the 
liquid contents of the stomach, previously propelled into the mouth through the minute 
pharyngeal aperture, they swallow. Though extremely voracious, they are capable of enduring 
long abstinence from food, a female Theridion quadripunctatum having been known to exist for 
eighteen months without nutriment in a phial closely corked. 1 When affected by thirst they 
will drink water freely. Their faeces consist of a white liquid containing oval, black particles 
of a greater degree of consistency. 
It has been already remarked that the aperture of the generative organs is situated 
between the branchial opercula in female spiders. At this part, which is often provided with 
opercular pieces of a more or less solid texture, the oviducts terminate. In the house spider, 
Tegenaria domestica, these oviducts are continued internally in an insensible manner with the 
ovaries, which form on each side of the intestinal canal a kind of sac, to whose parietes the 
ova are attached in a racemose manner. In the diadem spider, Epeira diadema, each ovary 
is divided by a transverse septum, and the eggs are laid at distinct periods. 
With regard to the function exercised by the remarkable organs connected with the 
digital joint of the palpi of male spiders there exists some difference of opinion. Taking 
anatomy as his guide, Treviranus arrived at the conclusion that the parts in question are used 
for the purpose of excitation merely, preparatory to the actual union of the sexes by means of 
appropriate organs situated near the anterior part of the inferior region of the abdomen. 
This view of the subject, which is very generally adopted, is opposed to that derived from 
physiological facts by Dr. Lister and the earlier systematic writers on arachnology, who 
regarded the palpal organs as strictly sexual, and recent researches, conducted with the 
utmost caution, have clearly established the accuracy of the opinion advanced by our 
distinguished countrvman. 2 
There are in the posterior part of the abdomen of spidery special organs for the secretion 
of the viscous matter of which their silken lines are formed. These consist of intestiniform 
vessels, varying in number and extent in different species, and having near their base, not far 
from the point where they open into the spinning-mammulae, some small, supplementary 
canals. When issuing from the minute papillae connected with the mammulae, the viscous fluid 
hardens immediately on exposure to the action of the air, forming delicate filaments, which 
vary greatly in number in different species. Those of each mammula unite in the first 
instance, and then the whole combine to form a common thread; so that the lines which 
serve such important purposes in the economy of spiders are composed of numerous filaments 
of extreme tenuity. 
The nervous system in spiders is ganglionic. A bilobed ganglion, situated in the anterior 
1 ‘ Researches in Zoology,’ pp. 302, 303. 
3 * Report of the Fourteenth Meeting of the British Association for the Advancement of Science,’ 
pp. 67-69. 
