There are no capillaries, but the blood is delivered into the tissues and finds its way, by irregular spaces or “lacunae,” into certain main venous channels or “sinuses.” There are three such in the cephalothorax, one median and the others lateral, considerably dilated in front, in the region of the eyes, and connected by transverse passages. By these the blood is brought back through the pedicle to the lung-books. In the abdomen also there are three main sinuses, two parallel to one another near the lower surface, and one beneath the pericardium. These likewise bring the blood to the lung-books, whence it is conducted finally by pulmonary veins (Fig. 186) back to the pericardial chamber, and thus, by the ostia, to the heart. The Spider’s blood is colourless, and the majority of the corpuscles are “amoeboid,” or capable of changing their shape. =Generative System.=—The internal generative organs present no great complexity, consisting, in the male, of a pair of testes lying beneath the liver, and connected by convoluted tubes, the “vasa deferentia,” with a simple aperture under the abdomen, between the anterior stigmata. The ovaries are hollow sacs with short oviducts which presently dilate to form chambers called “spermathecae,” which open to the exterior by distinct ducts, thus forming a double orifice, fortified by an external structure already alluded to as the “epigyne.” The eggs project from the outer surface of the ovary like beads, connected with the gland by narrow stalks, and it was not at first clear how they found their way into the interior cavity, but it has been ascertained that, when ripe, they pass through these stalks, the empty capsules never presenting any external rupture. The palpal organs have already been described. The spermatozoa, when received by them, are not perfectly elaborated, but are contained in little globular packets known as “spermatophores.” =Nervous System.=—The Spider’s central nervous system is entirely concentrated in the cephalothorax, near its floor, and presents the appearance of a single mass, penetrated by the oesophagus. It may, however, be divided into a pre-oesophageal portion or brain, and a post-oesophageal or thoracic portion. The brain supplies nerves to the eyes and chelicerae, while from the thoracic mass nerves proceed to the other appendages, and through the pedicle to the abdomen. The walls of the oesophagus are closely invested on all sides by the nerve-sheath or neurilemma.