PULMONARY. 325 



out simple threads. It is, I think, to the young Lycosoe that we 

 must attribute those which intersect the furrows of ploughed grounds, 

 whose numbers are rendered so apparent by the reflection of light 

 after sunrise. By chemical analysis, these threads exhibit the same 

 characters as the web of the spider: they are not then formed in 

 the atmosphere, as, for want of proper observation, ex visu, that ce- 

 lebrated naturalist, M. Lamarck, has conjectured. Gloves and 

 stockings have been made with this silk; but it was found impossible 

 to apply the process on a large scale, and as it is subject to many 

 difficulties, is rather a matter of curiosity than utility. This sub- 

 stance, however, is of much greater importance to the little animal 

 in question. With it, the sedentary species, or those which do not 

 roam abroad in search of their prey, weave webs of a more or less 

 compact tissue, whose form and position vary according to the pe- 

 culiar habits of each of them, and that are so many snares or traps, 

 where the insects on which they feed become entangled, or are 

 taken. No sooner is one of them arrested there by the hooks of 

 its tarsi, than the Spider, some times placed in the centre of his net, 

 or at the bottom of his web, or at others lying in ambush in a pecu- 

 liar domicil situated near and in one of the angles, rushes towards 

 his victim and endeavours to pierce him with his murderous dart, 

 distilling into the wound a prompt and mortal poison; should the 

 former resist too vigorously, or should it be dangerous to the latter 

 to approach it, he retreats, waiting until it has either exhausted its 

 powers by struggling, or become more entangled in the net$ but 

 should there be no cause of fear, he hastens to bind it by involving 

 the body in his silken threads, with which it is sometimes completely 

 enveloped. 



Lister says that Spiders dart their threads in the same way that 

 the Porcupine darts his quills, with this difference, however, that in 

 the latter, according to the popular belief, the spines are detached 

 from the body, whereas in the former, these threads, though pro- 

 pelled to a considerable distance, always remain connected with it. 

 The possibility of this has been denied. Be it as it may, we have 

 seen threads issuing from the mamillae of several Thomisi form 

 straight lines, and when the animals moved circularly, producing 

 movable radii. A second use to which this silk is applied by all 

 female Araneides, is in the construction of the sacs destined to con- 

 tain their eggs. The texture and form of these sacs are variously 



