$ 314. THE ARACHNOIDAE. 387 
CHAPTER VIII. 
ORGANS OF SECRETION. ‘ 
I. Urinary Organs. 
§ 314. 
With most Arachnoidae, there are small, usually multiramose, glandular 
tubes, which open into the cloaca. By théir structure and the nature of 
the fluid they secrete, they exactly resemble the Malpighian vessels of the 
Insecta, and like them, also, they have, for a long time, been regarded as 
hepatic organs; but now, they are known to be positively those of an 
urinary nature. The urine is usually accumulated in the cloaca, and con- 
sists of a troubled, dirty-white liquid, rarely reddish ; and, by direct light, 
is found to hold in suspension innumerable dark molecules. 
These organs appear to be absent with the Tardigrada, and Pycnogonidae. 
But, on the other hand, they are easily observed with many Acarina, where 
they consist of simple or ramose white tubes, situated between the append- 
ages of the stomach.” With the Phalangidae, there are two pairs of 
urinary canals which wind between the stomachic caeca.” With the 
Araneae, these organs are numerous, multiramose, and of a white or 
reddish color. Their very small branches penetrate between the different 
portions of the liver, and end in two principal trunks or ureters, which 
open into a cloaca provided with a kind of diverticulum. With the 
Scorpionidae, the organization in this respect is quite similar, and the 
canals, ramified in various ways, enter, some the interstices of the hepatic 
lobes, while others surround the digestive canal. They pour their product 
into the cloaca by two ureters which are situated back of the biliary 
canals, 
11 have discovered without trouble, these 
canals with the Hydrachnea, Gamasea, Trombi- 
dina, and Ixodea. Treviranus (Zeitsch. f. Phys- 
iol. IV. p. 189, Taf. XVI. fig. 8, no. n.) had already 
observed their insertion into the cloaca with Ix- 
odes. With Igvodes ricinus, where they are 
simple and fiexuous, I have seen them ascend 
-even to the anterior extremity of the cephalo- 
‘thorax ; this is entirely so with Ixodes ameri- 
-canus. The canals, which with Vigua, Treviranus 
(loc. cit. fig. 7, ¢. g.) has regarded as salivary or- 
gans, are certainly only the anterior extremities of 
the urinary vessels. The two species of Ixodes 
just mentioned have their cloaca filled with a 
white urine. 
2See Treviranus, Verm. Schrift. I. p. 31, Taf. 
IM. fig. 16,17. Tudlk (loc. cit. p. 249, Pl. IV. fig. 
17) who has been unable to trace these canals to 
their points of insertion on the intestine, has taken 
@ portion of them for salivary organs. 
3 Ramdohr (loc. cit. p. 208, Taf. XXX. fig. 2), 
and Treviranus (Bau d. Arach. p. 30, Taf. II. 
fig. 24) were only imperfectly acquainted with the 
urinary canals of the Araneae. They have been 
more exactly described by Brandt (Mediz. Zool. II. 
p. 89, Taf. XV. fig. 6, 17, or Ann. d. Sc. Nat, XIII. 
p. 183, Pl. IV. fig. 2, 3); but see, especially, Was- 
mann, loc. cit. p. 17, fig. 17, 21-23 (Mygale). In 
most species, the urine is of a dirty-white color ; 
but with Mygale, it is reddish. In several indi- 
viduals of a large species of Mygale preserved in 
alcohol, I have found, in the ureters, hard, reddish 
concretions which Duges (Aun. d. $c. Nat. VI. p. 
180) had already observed. Treated with nitric 
acid and ammonia, I obtained purpuric acid. 
4 See Treviranus, Bau d. Arach. p. 6, Taf. I. 
fig. 6, and Muller, loc. cit. p. 47, Taf. IT. fig. 22. 
This last anatomist says that these glandular canals 
communicate with the heart, but he has probably 
,confounded them with the blood-vessels. 
