IOl6 INSECTS AND AEACHNIDA 



(1) that which rapidly hardens on contact with the air, and which 

 is employed in the construction of the framework of the snare ; and 



(2) a viscid silk with which the entangling meshes by which prey is 

 caught are put in. The latter present beautiful objects for popular 

 observation, because the thread has strung upon it, as it were, 

 innumerable pearl-like globules in which the viscidity remains. 

 These beads are produced after the thread is drawn out by a 

 special vibratory action set up in the thread by the spider. 



The eggs of spiders are not objects of special optical interest, 

 but they afford opportunities for good embryological work, 1 and the 

 habits of spiders offer a good scope for industrious study in the field. 2 



1 See the work of Kishinouyi in Joitrn. Coll. Sci. Imp. Univ. Japan, vol. iv. 



2 See particularly McCook's American Spiders and their Spinning Work, 

 Philadelphia, 1889 and 1890, and the various papers of Mr. and Mrs. Peckham in the 

 American journals. 



