APPENDIX. 359 



and the secreted drops can unite and thus surround the thread upon all 

 sides. In order that the minute drops remain, it is necessary that the 

 foundation thread be dry when the Aggregate gland places its secretion 

 upon it. As the foundation thread is very strong, it will dry more quickly 

 if it consist of numerous fine threads instead of a single strand. For this 

 reason Apstein believes that the Aciniform gland secretes the foundation 

 thread. In the same way one can believe that the Pyriform gland forms 

 these threads. The foundation thread is more elastic than the dry threads 

 composing the snare itself. As the last named are formed from the Pyri- 

 form glands, there seems to remain only tlie Aciniform gland for the secre- 

 tion of the foundation thread. 



Note C. — Viscid Threads of Lineweavers' Snares. 

 (Chapter XIX., Page 351.) 



The viscid drops form, in masses close together, a large glutinous spot, 

 upon which small insects adhere. With Epeiroids the spirals of the snare 

 are formed of this thread. Among the Retitelarise Dr. Apstein found these 

 threads on the large, loose meshed web above the haljitation of the spider. 

 If an insect flies into this roof formed web it sticks to it. By its efforts to 

 escape the loose threads are broken, and the animal falls into the home 

 web, where it is seized by the spider. In no other web did he observe these 

 threads, and no other spider possesses these glands.^ 



The bearing of these facts upon the relations between the spinning- 

 work of Orbweavers and Lineweavers is manifest. Dr. Apstein contirms, 

 both from the standpoint of histology and field observation, the statements 

 concerning the viscid character of the web of Theridium, which I have 

 made with so great reserve. (See page 351.) He thus immensely strength- 

 ens the plausibility of supposing an easy passage from the spinningwork of 

 Lineweavers to that of Orbweavers, or in the reverse direction. Had tliese 

 observations reached my hand in the summertime, I should certainly have 

 made a thorough examination of the snares of Linyphia and Theridium. 

 At this date the matter is impossible, and must go over for another year. 



Note D. — The Swathing Thread for Insects. 



The Lobato or Lobcformed glands ^ occur only in Theridium steatoda 

 and some others of the above mentioned Retitelariaj. They have, there- 

 fore, only a limited extension, less so than the Aggregate glands. The 

 swathing threads are produced by the Lobcformed glands, as the spider has, 

 in her great lumen, always a large quantity of this material in reserve. 



' Apptoin, <ip. cit., pagre <)3. 



^ Lappciiformitrc Thcpo a])pear to he tlie Hiilbons or Tu})oros«^> glands of Meckel, ti^nired 

 Chapter II., page 44. 



