APPENDAGES 323 



tube within the bulb, ending in a blind sac, the " receptaculum 

 seminis," which projects into the haematodocha ; and it is the 

 aperture by which the sperm both enters and leaves the organ. 

 How the sperm is conveyed to the receptaculum was long a 

 matter for speculation, after the belief in a direct communica- 

 tion between the generative glands and the pedipalpi had 

 been abandoned. The process has been actually observed in the 

 case of a few spiders, which have been seen to deposit their 

 sperm on a small web woven for the purpose, and then, inserting 

 the styles of their palpal organs into the fluid,.to suck it up into 

 the receptacula seminis. This is probably the usual method of 

 procedure, though it may be true, as some have asserted, that the 

 palp is sometimes applied directly to the genital orifice. 



The receptaculum and its tube being thus charged with sperm, 

 it is the function of the haematodocha to eject it by exerting 

 pressure on its base. For this purpose the haematodocha is in 

 communication with the cavity of the tarsus, from which, in 

 copulation, it receives a great flow of blood, and becomes greatly 

 distended. Bertkau believes that he has detected very minute 

 pores (meatus sanguinis) communicating between the haemato- 

 docha and the receptaculum, and allowing some of the blood- 

 plasma from the former to mingle with the semen, but this 

 appears to be very doubtful. 



The Legs are uniformly eight in number, and are seven- 

 jointed, the joints, counting from the body, being the coxa, 

 trochanter, femur, patella, tibia, metatarsus, and tarsus) In a 

 'few cases, through the presence of false articulations, i.e. rings of 

 softer chitin, this number appears to be exceeded. Some of 

 the Palpimanidae (see p. 398) were at first thought to have 

 only six joints on their anterior legs, but the tarsus is present, 

 though very small. 



In the case of most spiders, the legs take a general fore and 

 aft direction, the first pair being directed forwards, the second 

 forwards or laterally, and the third and fourth backwards. In 

 the large group of " Crab-spiders " (Thomisidae), and in many of 

 the Sparassinae, all the legs have a more or less lateral direction, 

 and the spider moves with equal ease forwards, backwards, or 

 sideways. The legs are usually more or less thickly clothed 



1 Pickard-Cambridge, in his Spiders of Dorset, names them exinguinal, coxal, 

 Jeinoral, genual, tibial, metatarsal, and tarsal. 



