LAWSON, ON LIMAX MAXIMUS. 23 
Istly. Because it is not discoverable. 
2ndly. Because the rootlets of the veins terminate by aper- 
tures. 
8rdly. Because the whole of the viscera in the posterior part 
of the body are completely unattached below to the venous 
integument; and as the principal arterial supply is to the 
inferior surfaces, had there been any intervening series of 
vessels, the integument and viscera would be adherent to each 
other in this locality. The arteries are composed of nucleated 
muscular fibres, having buried in them clusters of calcareous 
granules, which give the snow-white colour to those vessels. 
I cannot say I have been enabled to confirm the truth of 
Von Siebold’s assertion, that the arterial extremities are 
formed of calcareous particles alone, the organic tissue being 
completely absent ; for in every specimen I examined, where 
it was possible to arrive at any clear decision, I most dis- 
tinctly observed, mingled with the lime-granules, long, nu- 
cleated endoplasts. The veins, as I before stated, are merely 
channels ploughed in the musculo-fibrous tissue of the skin, 
covered on their inner surface by a fold of transparent mem- 
brane; the great lateral vein of either side begins near the 
caudal extremity of the body, and travels forward horizontally 
to the lung-sac, at a distance of about + inch from the median 
sulcus of the foot. It increases in calibre as it approaches 
the lung, and on its journey receives several branches from the 
upper and lower divisions of the integument.* 
The pericardial gland or kidney, as it has been styled, is, 
in my opinion, no more an urime gland than is the heart or 
liver; nor, indeed, can I see any just reason why it has 
received this appellation ; for I conceive the assertion of 
Jacobson,+ that it contains uric acid, is of no weight whatever, 
seeing that it is based upon the idea that murexide is pro- 
duced when the dried kidney has been subjected to the action 
of nitric acid and ammonia. Undoubtedly these reagents give 
rise to a reddish stain (which I fancy does not need the am- 
monia to its production), but it is equally true that a portion 
of the liver, when placed under similar conditions, will give 
apparently the same results. Moreover, the statement that 
this gland possesses an excretory duct is entirely without 
foundation, and I can only account for its origin, by sup- 
posing that in emaciated mdividuals the rectum has been 
mistaken for a duct leading to the respiratory orifice. Not- 
withstanding the most patient and persevering endeavours 
* For the development and characters of the blood, see the admirable memoir 
of Mr. Wharton Jones (‘ Phil. Trans.,’ 1846), to which nothing can be added, 
+ Meckel’s ‘ Archives,’ vi, p. 870, 1820, 
