112 



THE POPULAR SCIENCE MONTHLY. 



aabited by people in the stone-using phase 

 jf life. J. S. Patterson. 



Beelin Heights, Onio. 



"A SPIDEK'S ENGINEERING." 



Mr. Editor : The inquiry respecting the 

 way in which 6piders bridge chasms and 

 streams, which is made in the note with 

 the above heading, upon page 635 of the 

 March number of this journal, has been 

 often and satisfactorily answered by Eng- 

 lish writers, 1 and the following is given 

 merely as a confirmation of their more ex- 

 tended observations : 



In March, 1866, I had taken a living 

 male and female JSFephila plumipes (some- 

 times called the " silk-spider of South Caro- 

 lina") to the photographic establishment 

 of Mr. Whipple, of Boston ; while waiting 

 for the taking of their pictures, and stand- 

 ing about six feet from the wire frame upon 

 which was extended the female's web, I saw 

 the little male suddenly cease climbing about 

 the frame, and take position upon its upper 

 margin; in a few seconds a silken thread 

 floated near me ; I allowed it to adhere to 

 my sleeve ; the spider then turned about, 

 and made several vigorous pulls upon the 

 line, as if to ascertain its fixity of attach- 

 ment ; when satisfied of this, he rapidly 

 made his way toward me, but, in order to 

 observe the act again, I hung my end of the 

 line over the frame, so that he was left 

 where he started ; after a few turns he took 

 position as before, with his abdomen ele- 

 vated and directed toward the spot I had 

 occupied ; presently a fine line shot out 

 from his spinners, and pursued an undulat- 

 ing course until it reached beyond the spot 

 I had occupied, and began to rise toward 

 the large ventilating cupola in the centre of 

 the room ; the spider would occasionally 

 turn and try the line as before, but it did 

 not become attached, and he did not em- 

 bark upon it. 



Feeling now quite sure that the current 

 of air toward the ventilator both deter- 

 mined the spider's preparatory action and 

 the progress of the line, I removed this line, 



1 Blackball, " Spiders of Great Britain and Ire- 

 land" (Introduction, p. 11); Journal of Proceedings 

 of Linnajan Society, vol. vii. ; Transactions of Lin- 

 na;an Society, vol. xv., p. 455. 



and blew gently upon the spider in the op- 

 posite direction ; he immediately turned 

 about, elevated the abdomen as before, with 

 the wind, and soon a line was carried in this 

 direction for as long and as far as my breath 

 could reach, and no farther. This was 

 repeated with the same result in various 

 directions. The extremity of the line 

 appeared blunt and a little enlarged, which 

 is in accordance with the view of Black- 

 wall respecting the way in which it is start- 

 ed : 



"The extremities of the spinners are 

 brought into contact, and viscid matter is 

 emitted from the papillae; they are then 

 separated by a lateral motion, which ex- 

 tends the viscid matter into filaments con- 

 necting the papillae; on these filaments the 

 current of air impinges, drawing them out 

 to a length which is regulated by the will 

 of the animal, and, on the extremities of 

 the spinners being brought together, the 

 filaments coalesce, and form one compound 

 line. ... If placed upon rods set upright 

 in glass vessels with perpendicular sides, and 

 containing clear water, they in vain attempt 

 to escape from them in a still atmosphere. . . . 

 " The lines produced by spiders are not 

 propelled from the spinners by any physical 

 power possessed by those animals, but are 

 invariably drawn from them by the mechan- 

 ical action of external forces." 



It is not so very strange that an Ameri- 

 can journal should reproduce the note which 

 suggested this communication, without in- 

 corporating the desired information, since 

 very few papers upon spiders have appeared 

 in this country; but the conductors of 

 Ilardwicke's Science Gossip, in which it first 

 appeared, must have been strangely ob- 

 livious of the already-quoted English ac- 

 counts of the subject. 



But this oversight is pardonable when 

 compared to what occurred in Scribner's 

 Monthly for May, 1872, in an account of 

 spiders, evidently a compilation. The com- 

 mon garden spider is represented head up- 

 ward in the centre of a web composed of 

 concentric circles. Now, every one that has 

 really examined a so-called geometrical web 

 knows that it consists of a spiral line, and 

 never of circles ; and also knows that the 

 Epeiridai are as averse to reposing head up- 

 ward as human beings are to assuming the 



