444. THIRD REPORT — 183o. 



the history of the toad^ I have merely employed a remarkable 

 example of the fact." 



Observations relative to the Structure and Functions of 

 Spiders. By John Blackwall, F.L.S. 



During the last three years the author has been engaged 

 occasionally in conducting experiments having for their object 

 the determination of a highly interesting question in physiology, 

 namely, Avhat are the true nature and functions of the remark- 

 able organs connected with the fifth or terminal joint of the 

 palpi of male spiders ? The opinion advanced by M. Treviranus, 

 and adopted by M. Savigny, that those parts are instruments 

 employed for the purpose of excitation merely, preparatory to 

 the actual union of the sexes by means of appropriate organs 

 situated near the anterior extremity of the inferior region of the 

 abdomen, is in direct opposition to the views of Dr. Lister and 

 the earher systematic writers on arachnology, who regarded 

 them as strictly sexual ; and the results of the author's investi- 

 gations clearly demonstrate the accuracy of the conclusion 

 arrived at by our celebrated countryman. 



In the spring of 1 So I Mr. Blackwall procured young female 

 spiders of the following species, Epeira diadema, Epeira apo- 

 clisa, Epeira calophylla, Epeira cucurhitina, Theridion ner- 

 vosum, Theridion denticulatum, Agelena labyrinthica, &c., and 

 having placed them in glass jars, fed them with insects till they 

 had completed their moulting and attained maturity, which is 

 easily ascertained in most instances by the perfect development 

 of the sexual organs. He then introduced to them adult males, 

 taking care to remove the latter as soon as a connexion had 

 been consummated in the usual manner, by the application of 

 the palpal apparatus to the orifice situated between the plates 

 of the spiracles in the females. He never in any instance suf- 

 fered the sexes to remain together any longer than he found it 

 convenient to continue his observations, and remarks that their 

 union, however prolonged and undisturbed, was invariably ac- 

 complished in the manner stated above. After a lapse of se- 

 veral weeks the females thus impregnated respectively fabricated 

 their cocoons, and deposited their eggs in them, all of which 

 proved to be prolific ; affording a complete refutation of the 

 opinion promulgated by M. Treviranus. 



That there might not remain the slightest doubt, however, 

 on the mind of the most fastidious inquirer, in the summer of 

 1832 the author brought up from the c^g young females of the 

 species Epeira calophylla and Epeira cucurhitina, which, when 



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