WATER ENTERING THE BLOOD. 117 



exit carry away a portion of the blood ? It will, and 

 does, as any one may i^rove experimentally. Agassiz 

 has described it in detail, apropos of the 3Iactra/' and 

 suggests that the pores of the fish may have a similar 

 office. In the Actinice and Acalephce the free passage 

 of water to and fro is well known. In several Anne- 

 lids (Eunice, Nereis, &c.), I have little doubt that the 

 openings which exist on each side of the body, between 

 every two feet, and which permit the passage of the 

 ova into the surrounding water, are aquiferous tubes, 

 through which the water passes to and fro. These 

 openings were first described by Eathke ; and Siebold 

 admits that through them the water may probably pass. 

 M. Quatrefages, however, a great authority on the sub- 

 ject of Annelids, is disposed to deny the existence of 

 these openings : " J'ai vu chez TEunice sanguine des 

 apparences rappelant un pen 1' observation de Rathk^ ; 

 mais ces orifices, s'ils existent, ont evidemment pour 

 objet de servir a la sortie des oeufs ; c'est la du moins 

 ce que Tanalogie permet d'admettre. Je n'ai jamais vu 

 pondre on ^jaculer une Annelide errante."*)* What M. 

 Quatrefages has not been fortunate enough to have 

 seen, has several times been witnessed by me. I have 

 seen the eggs issuing from these openings, the exist- 

 ence of which he is inclined to dispute ; and inasmuch 

 as these eggs may be seen floating in the general cavity 

 of the body, before they issue through the openings at 

 the side, there seems little room for doubt on the 



* Siebold U. KoLUKER—ZeitschnJi./. Wissen. Zoolog. vii. 176. 

 t Quatrefages in Annales des Sciences Nat., 1850 ; xiv. 298. 



