Maturation and Fertilization in Theridium. 239 



yolk layer trom the inner. Before staining or imbedding: the outer 

 egg membrane was removed in 70" ^ alcohol. Eggs to be sectioned 

 were rapidly deliydrated, eosin being added to the absolute alcohol 

 in order to made them visible in the paraffine, cleared in xylol for 

 about 30 minutes, then imbedded for from 2 to 4 hours in paraffine 

 at a melting grade of 54" C. Sections were cut of 7 /t thickness, 

 then stained in Delafield's haematoxyline followed by alcoholic 

 eosin. Many total mounts were also made since these are favorable 

 for the findiirg of the polar spindles; here whole eggs were stained 

 in Delafield's haematoxyline for about 5 minutes, then destained 

 until the outer yolk layer is nearly colorless. But is is not possible 

 to so stain whole eggs that structures within the inner yolk stand 

 out clearly. 



I. The female Copulatory Organs. 



Bertkau (1875a) first found tubes leading from the receptacula 

 seminis towards the oviducts, and thought these two might be in 

 open communication. Eaieeton (1882) described the condition in 

 the Tlieridiidae as follows: "The epigynum consists of two round 

 spermathecae near the genital opening of the female, from each of 

 which run two tubes, one, usually the larger and longer, to a hole 

 outside the body, the other, usually small and short, into the ovi- 

 duct near its mouth." Theridium tepidariorum corresponds to Einieeton's 

 description, and I give an enlarged drawing of a cleared mount of 

 its genitalia in Fig. 44, PI. 5. Anterior to the transverse genital 

 aperture (vulva) is a hardened chitinous plate, the epigynum, con- 

 taining a depression ; from the latter leads right and left an opening 

 (Ap) into a coiled tube {T. 1) that opens into the receptaculum seminis 

 {Bee) of the same side; then from the latter a narrow tube (T. 2) 

 leads back towards the oviducts and probably opens there into them 

 since its canal appears to end as an open groove on the surface of 

 the tube. 



II. The Ovarian Egg. 



Ovaries of mature individuals contain only oocytes, and no 

 oogonial mitoses. As Bertkau (1875a) found for other species, this 

 one too has the oocytes during their growth period disposed along 

 the outer wall of the ovarial tubes, in stalked follicles produced by 

 an outpushing of the epithelium; he also found, what my material 

 did not allow me to determine, that these ova when full grown fall 



16* 



