& 
350 Prof. E. Claparéde on the Structure of the Annelida. 
justice to the beautiful investigations of M. Milne-Edwards. It 
is to be regretted that he has not shown the same favour to 
Rud. Wagner and Rathke. The distinction which he establishes 
between the arterial and venous currents appears to me to be 
very just in its principal features. The same view has been 
entertained by some authors; witness the name of nervarteria 
given by Delle Chiaje to the ventral vessel—that is to say, the 
aorta in the sense of M. de Quatrefages. 
The existence of blood-corpuscles in the vessels of certain 
Annelida is now-a-days indubitable. M. de Quatrefages, in his 
‘Histoire Naturelle des Annelés,’ admits three examples of this 
—the Glycere, Phoronis, and the Syllidea. The latter alone is 
of any value. Thus in the Glycere the red corpuscles belong 
to the liquid of the perivisceral cavity ; and as to Phoronis, that 
genus can hardly retain its place among the Annelida. But, 
without speaking of an old observation of Rud. Wagner with 
regard to a Terebella, which has, moreover, been confirmed by 
M. KoOlliker, other examples may be cited. In the present 
memoir true blood-corpuscles will be found described in the 
Opheliea, the Cirratulea, and the Staurocephale. 
Respiratory Apparatus. 
M. de Quatrefages has made science actually go back as re- 
gards the structure of the organs of respiration. ‘This is the 
weakest part of his book—weak in the introduction, weak in the 
general remarks on each family. The branchie, in the opinion 
of the honourable Academician, have a proper structure, which 
enables them to be always distinguished. ‘ These organs,” he 
says, “are characterized by a single canal, at and from which 
afferent and efferent vessels arrive and depart. This canal, the 
proper walls of which are sometimes visible and sometimes in- 
distinct, is surrounded by a diaphanous substance which seems 
to be produced by the thickening of the dermis. In this sub- 
stance are hollowed out ampulliform lacune more or less deve- 
loped, and always destitute of proper walls. The whole is 
surrounded by an extremely fine epidermis, which presents no 
appreciable structure. Finally, this epidermis is beset with 
vibratile cilia...... At the end of a variable time the branchia 
contracts, although no muscular fibres can be discovered in it. 
The ampulle empty themselves, so as sometimes to disappear 
entirely. The blood flows through the central canal of the 
branchia, and, on arriving at the base of the organ, passes into 
the efferent vessel. In this movement of return it necessarily 
meets the venous blood, and cannot but become mixed with a 
certain quantity of blood which has not undergone the action of 
the air.” 
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ae ee 
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