C80 THE ARACHNOIDAE. § 308. 



tube, of nearly equal size throughout, without a stomachic dilatation and 

 without caeca, which opens by an anus at the posterior extremity of the 

 body.<'-" 



§ 308. 



The Salivary glands exist with, perhaps, all the Arachnoidae; for, they 

 are found even in many of the lower forms, where their presence would be 

 least expected. With the Tardigrada, there are on each side of the suck- 

 ing apparatus, large, lobulatcd glandular tubes, which appear to be organs 

 of this nature, although their outlets have not yet been distinctly traced.*'' 

 With the Oribatea, there is at the anterior extremity of the body, a pair 

 of similar tubes, but simple and colorless, which extend to the mouth, 

 and have undoubtedly a salivary function.'-' 



With Ixodes, these organs are extraordinarily developed, consisting of 

 two large masses of vesicles situated on the sides of the anterior part of the 

 body, and opening by short ducts into two multiramose excretory canals. 

 These last, whose walls are traversed by a solid spiral filament, open into 

 the buccal cavity at the base of the lip-like process.*"' 



With the Araneae, a slit in the upper lip leads into a cavity situated 

 above the palate, and at the base of this cavity is a transparent, glandular 

 mass, which, very probably, secretes the saliva ; this flows up through the 

 slit in question, and moistens the substances from which the animal ex- 

 tracts its food.'^' As salivary organs should also be considered the two 

 pairs of glandular tubes, which, with the Scorpionidae, are situated on the 

 sides of the anterior part of the body, and extend forwards to open into 

 the oesophagus.'''' 



With the Araneae, and Scorpionidae, there is a Liver distinct from the 

 digestive tube, which, for a long time was regarded as an adipose mass. 

 With the Tardigrada, Acarina, Pycuogouidae, and Opilionina, the walls of 

 the stomachic appendages are of this nature, for they are glandular and com- 

 posed of granular and usually yellowish-brown cells. '*^' With the Araneae, 

 the brown or dirty-yellow liver is very voluminous, filling a large portion 

 of the abdominal cavity, and enveloping most of the other viscera. 



At first sight, it appears to be a compact mass, but, further examined, 

 it is found composed of numerous multiramose, closely-aggregated caeca. 

 The walls of these are thick, and crowded with hepatic cells, and they open 

 into the digestive canal near its middle by four short hepatic ducts. ''^' 



9 With the Scorpionidae, the anus is situated on ^ See Mailer, loc. cit. p. 52, and Ifemport, 



the penultimate caudal segment. Philosoph. Trans. 1S43, PI. XV. fig. 39. 



1 See Doyire, loc. cit. p. 321, PI. XllI.-XV. " 'Vf'iih the Tardigrada, Acarina, and Opilionina, 



2 I have seen these glandular tubes with Hoplo- ^^ \f^s.%i, I have seen, distinctlj', hepatic cells in 

 pkora, Zetes, and Oribates. the walls of the stomachic appendages. See also 



3 The salivary glands of Ixodes ricinus resem- Doyire, loc. cit. p. 327, PI. XV. 



ble exactly the botryoidal ones of many of the In- " Treviranus (I5au d. Arachnid, p. 30, 4", Taf. 



secta. II. fig. 24, dd., and Taf. V. fig. 47) had already 



The secretory vesicles of the saliva are filled with observed the communication between the liver and 



transparent nucleated cells and surrounded by "le digestive organs. The remaining points in the 



numerous ramified tracheae with which it is im- structure of this organ have been rightly estimated 



possible to confound the excretory ducts of these ''.V Dngi/i (Ann. d. Sc. Nat. VI. p. 179), Grube 



glands; for with these last the spiral turns of thin ('"c cit. p. 299), and fVasmann (loc. cit. p. 13, fig. 



filament are very wide apart, while, in the tracheae, 17, m. n., 20-22). See also Ou)en, Lectures, &c., 



the spiral windings are very close together. P- 258, fig. 110, i. i. 



< This glandular apparatus has been seen by 

 fVasmann (loc. cit. p. 8, tig. 16) with Mygale i 

 I liave found it also with other Araneae. 



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