48 Facts in the Physiology of Sjyiders and Insects. — BlachweU. 



spinners by a current of air admits of an easy explanation. As a 

 preparatory measure the extremities of the spinners are brought into 

 contact, and viscid matter is emitted from tlie papilla; ; they are then 

 separated by a lateral motion, which extends the viscid matter into 

 filaments connecting the papillae ; on these filanieuts the current im- 

 pinges, drawing them out to a length which is regulated by the will of 

 the animal, and on the extremities of the spinners being again brought 

 together, the filaments coalesce and form one compound line. 



The only legitimate deduction from the foregoing experiments, 

 which have been frequently repeated under every variety of circum- 

 stances likely to affect the result, appears to be that the lines produced 

 by spiders are not propelled from the spinners by any physical power 

 possessed by those animals, but that they are invariably drawn from 

 them by the mechanical action of external forces. 



Sec 2. The importance of the greatly diversified form of the re- 

 markable organs connected with the radial and digital joints of the palpi 

 of male spiders, in aftbrding valuable specific characters in numerous cases 

 in which species so closely resemble each other in size, color and econ- 

 omy, as scai'cely to be distinguished, except by minute differences in their 

 external structure, is beginning to be duly appreciated by arachnolo- 

 gists, whose attention hitherto has been almost exclusively directed to 

 investigations having for their object the discovery of the function 

 performed by those organs — a highly interesting problem undoubtedly, 

 the solution of which long continued to exercise the skill and ingenuity 

 of zootomists and physiologists. Though the palpal appendages are 

 now known to have a strictly sexual character, and have, in fact, been 

 demonstrated by experiment to constitute a true intromittent organ, 

 absolutely essential to fecundation, yet no direct communication has 

 been ascertained to exist between them and certain vermicular vessels 

 situated in the abdomen, and usually regarded as testes, whose ducts 

 terminate in ' the space intermediate between the branchial stigmata. 

 M. Duges has attempted to oljviate this difficulty by shrewdly suggest- 

 ing that these parts may have been voluntarily brought together 

 prior to the act of copulation, and then proceeds to ask, " le conjonc- 

 ture" (palpal organ) " ferait-il alternativment I'oflice de siphon ab- 

 sorbant et dorgane ejaculateur ?" — a question which he answers in the 

 following terms : "cela se pent, mais je n'ai rien pu observer, qui 

 justifiat directement cette conjecture." 



In a concise notice of a work on the habits of the Arachnida, by A. 

 Menge, given in the "Reports on Zoology," for 1843 and 1844, p. 195, 

 published by the Ray Society, the following passage occurs : " Copu- 

 lation. It v.as reserved for the author to solve the physiological 



