Maturation and Fertilization in Theridium. 241 



spindles. It is difficult to ascertain exactly the comparative lengths 

 of these loops since they are twisted, yet in some cases two of like 

 lengths seem to lie close together, such as those lettered A,a. . .E, e. 

 Probably each such pair represents a bivalent element, that is, 

 corresponding paternal and maternal chromosomes, in accord with 

 what is now known to be general for the germ cells at this stage. 

 Each of the single loops would then be univalent; rarely do any 

 show a trace of a longitudinal split, yet an indication of sucli a 

 condition is seen" at K in Fig. 2b. 



In a single nucleus of this stage there was a deep staining 

 dense rod at some distance from the chromosomes (x Fig. 1, and 

 enlarged in Fig. 2c). This has the same size and appearance as 

 a spermatozoon, except that it is straight and not bent: but I 

 hesitate to consider it a spermatozoon because it would be very 

 unusual for a sperm to, penetrate through the nuclear membrane, 

 and because it was found in only one nucleus. 



III. Stage of the First Maturation Spindle. 



I have described elsewhere how at oviposition a j^ellowish 

 drop of viscid fluid escapes first from the vulva, and how the eggs 

 are next discharged into this drop; while Schimkewitsch (1887) 

 demonstrated that this viscid substance is the secretion of a gland 

 that opens into the oviduct. For about half an hour afterward 

 this fluid remains viscid, thus holding the eggs in a compact mass 

 while the mother is spinning the cocoon; then it dries, leaving a 

 fine film upon each egg but no longer cementing the eggs together. 

 Before this drop hardens the eggs are polygonal, afterwards they 

 become rounded. 



At oviposition (not within the follicle) the egg has an outer 

 thicker, homogeneous membrane, probably formed from the secretion 

 of the oviducal cells (Fig. 5 Mem). The outer surface of this 

 membrane is thickly beset with minute tubercles; these stain with 

 eosin while the remainder of the membrane remains colorless, there- 

 fore the tubercles may represent condensed droplets of the viscid 

 secretion referred to above. The vitelline membrane proper is not 

 well defined, but is simply a slight condensation of the outer cyto- 

 plasm (Figs. 5, 9, PI. 57 ; Fig. 42, PI. 5). The yolk consists of two 

 layers: an outer one of radial columns, and an inner one where no 

 such arrangement holds (Fig. 3, PL 4). The columnar layer contains 



