180 REPORT— 1851. 



from a similarity in the structure and disposition of the utero-ovarian organs ; 

 while the male organs in these two worms strikingly differ in structure and 

 arrangement, the female systems are almost identical. To this system in the 

 Earth-worm, again, M. Quatrefages has erroneously applied the description of 

 '■'^ Secretory pouches^' " poches secretrices venant s'ouvrip sur le dos par les 

 canaux renflis*." The primary longitudinal trunks are similar in number and 

 disposition to those of the Leech ; the direction of the blood-curreut is also 

 the same. In the dorsal longitudinal half of the system, the blood moves from 

 the tail towards the head ; in the ventral, contrariwise. In the Earth-worm, 

 in this respect distinguished from the Leech, the intestine is only tied to the 

 integuments at the interanuular points; the intervals or segmental spaces 

 being left as chambers, containing a small quantity of viscid corpusculated 

 fluid, which is the peritoneal fluid of this worm. The interposition of 

 a fluid stratum in this part involves other anatomical modifications, which 

 still further separate the organization of the Earth-worm from that of the 

 Leech ; the spongy vessels described as occupying this part in the latter are 

 absent in the former. The intestine as well as the integuments are reticu- 

 lated with elaborate capillary plexuses (fig. 7,/), both of which enact a part 

 in the process of respiration. The complex character of the peripheral cir- 

 culation in the Earth-worm, proves with great force the inverse proportion 

 which in all Annelids exist between the volume of the blood-proper and that 

 of the peritoneal fluid. In this worm accordingly, from the denseness of the 

 peripheral capillaries, the physiologist may predicate almost the absence of 

 the peritoneal fluid. 



Superadded to the primary median blood-channels (fig. 7, a and d, c), a 

 minor lateral system, founded upon the latero-abdominal trunk, may be de- 

 monstrated in the Earth-worm as in the Leech ; in all essential particulars in 

 the two cases, the main trunk of the system and its branches are the same. 

 The Earth-worm is essentially a water-breathing animal ; it dies in pure water 

 from starvation, in dry air from asphyxia; the character of the circulatory 

 fluids obviously suggest the above inferences. The larger blood vessels, where- 

 ever they come into relation with the intestine, are more or less embraced by 

 the peritoneal membrane of this canal, and in this, as in all worms, this mem- 

 brane is intimately adherent to the biliary gland-cells. In its foldings, this 

 structure, with its yellow-coloured cells, more or less envelopes the vessels, 

 and gives to them the appearance of being surrounded by a spongy pigmental 

 coat. M. Merren, in the refinement of his dissections, saw in this covering a 

 separate structure, and distinguished it as the " ChloragogenaV An order 

 of vessels in the circulating system of the Earth-worm now presents itself, to 

 which there exists no parallel in that of the Leech. At the segments occu- 

 pied by the testicular masses, the great dorsal trunk detaches symmetrical, 

 lateral, successive branches (fig. 1,b,b) of large calibre, to the number of 

 seven or eight, which vertically embrace the oesophageal intestine, and empty 

 themselves, without subdivision, into the ventral trunk. By Duges and all 

 subsequent writers these vessels have been called the mojiiliform hearts. 

 Quatrefages, in his recent and beautiful illustrations, published in Crochard's 

 edition of the ' Regno Animal,' has depicted these vessels as consisting of a 

 succession of beads, as moniliform as those given in the lectures of Sir Everard 

 Home, or by the ancient Willis, in his classic work 'De Anima Brutorum !' 

 In real truth, these vessels are not in the slightest degree whatever monili- 

 form; they consist of nearly uniformly outlined cylinders ; the middle of each 

 vessel, however, is slightly bulged (fig. 7, V"). They constitute direct com- 



* Crochard's edition of the Regne Animal, Vol. Annelides, pi. 21. Extrait des recherches 

 inedites sux les Annelides, par M. de Quatrefages. 



