10 



AMERICAN SriDKRH AND TIIKIU SriNNINGWORK. 



Fir;. 31. Pyriform glands, caudate; A. cophinarla. 



these differently formed glands prejiare different secretions. However, the 

 only diffcronce wliicli Meckel obtained by applying a few reagents Avas that 

 the eyliiicb-ieal glands beeaine more eoagnlated tlirougli alcohol and acids 

 llian others. AVe may now enter upon a detailed description of these silk 



glands, for which I am particularly in- 

 debted to tlie admirable stud- 

 Detailed igg Qf j)j.g j3^^cholz and Lan- 



^^^^ dois,i and of Meckel. ^ In 



some measure, also, I liavc 

 drawn upon the English microscopists, 

 Messrs. Underbill 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 

 ado})ted 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- 

 ^yriorm ^^^ ^^ ^^^ ^^ ^^^^^ have 



been prosecuted. The py- 

 riform glands py.g, vastly exceed 

 the other forms in number, as there 

 are present in every s})inneret one 

 hundred or more. However, they 

 may not e.\ceed 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 



' Anatoinisclie TTntorsiiclimii;i'n iilici- ilcii Ban fler Araneiilcu : von l)r, Ueinhold Buchol/, 

 mill Dr. Leonard Landois. .\n'liiv Anatomic, I'liisiolojric iind Missrli. .Mod. Jalirganj;, ISfiS, 

 l)age 240 sq. (Lei])zifi;.) 



^ Heinricli Mcelvel : Mikrofrrapliiu uinifjer Driiscn .Vpiianitc dor niodcren Tliii'iv. .\n-hiv 

 f. Anat. Phys. (Berlin), 1840, page 1 sq., PL III. 



Fig. 32. Pyriform glands of Argiope. 



