40 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



FIG. 31. Pyriform glands, caudate ; A. cophinaria. 



these differently formed glands prepare different secretions. However, the 

 only difference which Meckel obtained by applying a few reagents was that 

 the cylindrical glands became more coagulated through alcohol and acids 

 than others. We may now enter upon a detailed description of these silk 



glands, for which I am particularly in- 

 debted to the admirable stud- 

 Detailed ieg of Drg B nc holz and Lan- 

 es rip- ^- i an( j Meckel. 2 In 

 tion. 



some measure, also, 1 nave 



drawn upon the English microscopists, 

 Messrs. Underhill and Meade. I have 

 tried, however, to confirm all statements 

 accepted by me by independent studies 

 of our own fauna. 



The secretions of Epeira diademata 

 on which spider most of the valuable 

 studies here referred to have been made, 

 are in not more than a thousand glands, 

 which are connected with an equal num- 

 ber of independent ducts. There are 

 three different sorts of these glands, 

 which are distributed to their own es- 

 pecial spinnerets. Each spinneret possesses a large and somewhat variable 

 number of small pyriform glands, and besides this one or more larger 

 glands. Concerning these I have 

 adopted substantially the conclu- 

 sions of Bucholz and Landois, which 

 are confirmatory, for the most part, 

 of the principal statements of Meck- 

 el, and which are almost wholly in 

 accord with my own stud- 



rm ies as far as they have 

 Glands. J 



been prosecuted. The py- 

 riform glands py.g, vastly exceed 

 the other forms in number, as there 

 are present in every spinneret one 

 hundred or more. However, they 

 may not exceed the less numerous 

 but considerably larger gland forms in quantity of secretions. They are ar- 

 ranged, as has already been said, in round clusters of about two millimetres 



1 Anatomische Untersuchungen iiber den Bau der Araneiden : von Dr. Reinhold Bucholz 

 und Dr. Leonard Landois. Archiv Anatomic, Phisiologie und Missch. Mod. Jahrgang, 1868, 

 page 240 sq. (Leipzig.) 



2 Heinrich Meckel: Mikrographie einigcr Driisen Apparate der niederen Thiere. Archiv 

 f. Anat. Phys. (Berlin), 1846, page 1 sq., PL III. 



Fni. 32. Pyriform glands of Argiope. 



