347 
1887.] Dr A. B. Griffiths on Hirudo medicinalis. 
ducts. The nephridia (“ segmental organs ”) open externally on the 
ventral side of the body. 
In Lumbricus the nephridium communicates internally by a wide 
funnel-shaped aperture (which is ciliated) with the perivisceral cavity, 
but in Hirudo it opens internally by a “ cauliflower-headed ” portion 
(the analogue of the funnel-shaped aperture of Lumbricus) into the 
perinephrostomial sinus. Each nephridium consists of five principal 
parts — (1) posterior lobe, (2) anterior lobe, (3) apical lobe, (4) the 
testis lobe, (5) the vesicle, with its duct, which opens externally. 
The nephridia of Hirudo are covered by a pigmented connective 
tissue. These pigments are no doubt the histohsematin of Dr C. A. 
MacMunn,* for he says in another paper — “ I have found that 
throughout the whole animal kingdom, in each tissue and organ, 
there are present colouring matters ” ( Proc . Birmingham Philosophi- 
cal Soc., vol. v. part 1, p. 211). I have shown in my paper f the 
presence of uric acid in the nephridia of the Oligochseta. 
In the present paper details are given of the extraction of uric 
acid from the nephridia or “ segment organs ” of the Hirudinea. 
The species taken for investigation was Hirudo medicinalis. The 
secretions of the nephridia were obtained from a considerable num- 
ber of freshly killed leeches, and examined by similar chemical and 
microscopical reactions as I have employed in my paper already 
cited, and in one “ On the Nephridia and Liver of Patella vulgata”% 
read before the Royal Society of London, June 16, 1887. It may 
he useful to give the details of the processes. The secretions were 
examined by two separate methods — - 
(a) The clear liquid from the nephridia was treated with a hot 
dilute solution of sodium hydrate, and then, on the addition of 
hydrochloric acid, a slight flaky precipitate is obtained, after some 
hours’ standing. These flakes were seen, under the microscope, to 
consist of various crystalline forms. On treating these crystals with 
nitric acid, and then gently heating with ammonia, the reddish- 
purple murexide is produced, which crystallises in four-sided prisms. 
The secretion alone, when treated with alcohol, deposits rhombic 
* Proc. Roy. Soc., No. 240, 1886, and Philos. Trans., 1886. 
+ “ Researches on the Problematical Organs of the Invertebrata, especially 
those of the Cephalopoda, Gasteropoda, Lamellibranchiata, Crustacea, Insecta, 
and Oligochseta,” read before the Royal Society, Edinburgh, May 16, 1887. 
% Proc. Roy. Soc., vol. xlii. (1887), p. 392. 
