CONTRIBUTIONS TO THE ANATOMY OF THE HIRUDINEA. 453 



taining dissolved hsemoglobin. In preserved Nephelis, hsemo- 

 globin crystals are sometimes found in the vessels. Colourless 

 amoeboid corpuscles occur in great numbers. Fig. 40 a, shows 

 these corpuscles from Nephelis ; fig. 40 b, from Hirudo as they 

 appear in the fresh state; fig. 40c, after treatment with 

 acetic acid, and fig. 40 d, after treatment with magenta. These 

 figures can leave no doubt about their being nucleated amoeboid 

 corpuscles. 



The blood in all these genera coagulates rapidly when with- 

 drawn from the body — filaments of fibrin or some allied sub- 

 stance may be seen forming upon the microscope-slide. 



vi. Vascular System — Ccelomic Spaces. 



The observations of the older anatomists upon the circulatory 

 system of leeches, observations by Du Rondeau, Knolz, Du- 

 trochet, Thomas, Delia Chiaje, Cuvier, Dillon, Spix, J. Miiller, 

 Wagner, Duges, and others, dating from the year 1782, admirably 

 summed up by Moquin Tandon,^ resulted in a general know- 

 ledge of the anatomical relations of four longitudinal trunks 

 and their main branches. No question as to the possible 

 relation of these to " coelom,^^ i. e. to the perivisceral spaces of 

 other worms, seems to have entered their minds. It was 

 reserved for Leydig- to show that in Clepsine, Piscicola, Pon- 

 tobdella, and Branchellion, the vascular trunks form two 

 distinct systems, a contractile and a non-contractile, con- 

 nected with one another at one or tw^o points only, and for 

 De Quatrefages^ to suggest the relation existing between 

 these systems and the closed vascular system on the one hand, 

 and the general perivisceral cavity on the other, as they exist 

 in chsetopod worms. Leuckart* was the first to insist upon the 

 homology between the blood spaces of the groiip generally and 

 the " coelom/^ which had by that time been recognised as of 

 such morphological importance in all the higher animals. 



1 ' Monogr. de la famille der Hirudinees,' 1846, p. 143. 



2 Leydig, ' Berichteu k. zoot, Anstalt zu Wiirzburg,' 1849. 

 ^ De Quatrefages, 'Ann. sci. nat. Zool.,' 1852. 



■• ' Die Mensch. Parasiten,' 1863. 



