ANATOMICAL NOMENCLATURE. 131 



that of a passive organ, receiving the sperm and transmitting it into the 

 genital cleft of the female under the pressure of the blood which enters 

 into the htematodocha through the meati sanguinis. 



The receptaculum, in the region of the embolus, is throughout its whole 

 length fine, smooth, and without pores. Further toward its closed extremity 



is a mass of minute ducts which pierce the walls, and which 

 ■p. . Wagner has named meati sanguinis, blood ducts. All spiders 



are provided with these ducts, and their role is to serve as con- 

 duits to the blood from the htematodocha into the receptaculum. 



The Tegulum is a quite thick plate of cliitine serving to cover in from 

 above and to protect the receptaculum. Many spiders, as the Attids, Thorn - 

 isids, and others, have here no chitinous conformation except the tegulum ; 

 but spiders which have a more complicated organism of this apparatus 

 are provided with many other auxiliary organs, in the form of laminse, 

 dentations, and excrescences of the most unique and varied forms. " The 

 embolus is an organ of a chitinous nature, for the most part subiliform or 

 having the form of a switch. At its extremity there is a small orifice 

 (Fig. 98, or), by which the sperm enters and issues. The articulation of 

 the embolus with the tegulum may be mobile or immobile. 



The action of the above parts is as follows : The male applies to the 

 genital cleft of the female the exterior face of his palp, and by numerous 



contractions of the abdomen, in which the subcutaneous muscles 



' take part, forces the blood through the orifice into the cavity 

 of the hsematodocha, which it expands, pushes out the copulatory appa- 

 ratus, and having by way of the blood ducts penetrated into the cavity 

 of the receptaculum seminis, impels the sperm through the embolus into 

 the genital cleft of the female. When the blood begins to abate, returning 

 into the body of the male it fills anew the sac as full as at first, an opera- 

 tion which is repeated until fecundation is terminated ; then the palp is 

 withdrawn from the genital cleft, the hasmatodocha contracts, and the 

 tegulum resumes its position. ^ 



' La Mue des Araign^es, M. Waldemar Wagner, Ann. Sc. Nat. Zool., 18S8, 307-371. 



