358 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



characteristic of Uloborus, Hyptiotes, and Dictyna are secreted by what he 

 calls the Cribellum gland. The Lobate glands prepare the threads by 

 which the insect is swathed previous to being eaten. Possibly, however, 

 several glands take part in furnishing the swathing bands. The Pyriform 

 glands secrete the spinningwork which forms the snare proper, or the 

 seizing tissue, together with the dragline and trapline. I would venture to 

 add to this the suggestion that the same glands must also secrete the fila- 

 ments which form the ballooning thread and floating strands known as 

 gossamer. The function of the Aciniform glands and Ampullate glands, 

 according to Dr. Apstein, is not known. (See Figs. 348-354.) 



347 



FIG. 346. Spinning spool of Epeira diademata pyriform gland. X 188. FIG. 347. Longitudinal section of 

 a spool of the aggregate gland. X 188. FIG. 348. Spinning spool of the glandula aciniformis. X 188. 

 FIG. 349. Longitudinal section of a spool of the ampullate gland. X 188. FIG. 350. Longitudinal sec- 

 tion of spool of glandula tubuliformis. X 188. (After Apstein.) FIG. 351. An aciniform gland. X 30. 

 FIG. 352: A pyriform gland. X 105. FIG. 353. Longitudinal section of pyriform gland. X 105. FIG. 

 354. The spinning glands of Epeira diademata in natural site. X 9. (After Apstein.) ac, aciniform 

 glands; p, pyriform glands; am, ampullate glands; ag, aggregate glands; t, tubeformed or tubular 

 glands (glandulse tubuliformes.) 



NOTE B. SECRETION OF VISCID BEADS. 



Dr. Apstein is inclined to think that the foundation thread is created 

 from the "Aciniform gland." As soon as the foundation is stretched the 

 spools of the Glandules Aggregates (the Aggregate or Treeform Glands) are 

 pressed on it, and leave on it a little drop of viscid secretion. The three 

 spools stand close together on the superior spinneret that is to say, their 

 mouths lay close together. If now the two superior spinnerets be pressed 

 to the foundation thread, the six spools of the two sorts will embrace it, 



