THE COASTS OF SICILY. 269 



animals. The prolongations of the stomach are all 

 carried into the interior of these small protuberances, 

 and consequently the chyle, on issuing from the 

 intestine, is at once brought into the midst of the 

 respiratory apparatus, where it cannot fail to un- 

 dergo immediately the vivifying influence which it 

 requires. Such are the facts which led me to that 

 theory of phlebenteriim, which, after being violently 

 attacked by several French naturalists, has met with 

 a much more favourable reception amongst foreigners, 

 and more especially amongst German zoologists. In 

 the detailed examination of the remarkable group 

 which furnished me with my facts, I was necessarily 

 led into some errors; but time and renewed re- 

 searches have only tended more and more to confirm 

 the essential and general results which I discovered.* 

 When considered from this point of view, the 

 class of the Mollusca is indeed very remarkable. 

 Without departing from its limits, we find the cir- 

 culation exhibiting the most different degrees of 

 complication, and that even in animals often closely 

 allied to one another, and in which we might there- 

 fore have been led a priori to believe that the or- 

 ganisation was almost identical. Nevertheless, the 

 circulatory system still remains incomplete, there 

 being no perfect continuity between the venous and 

 the arterial apparatus. Consequently, the blood 

 which was propelled from the heart cannot return 

 to it until it has been diffused through all the inter- 

 organic spaces or lacunae, and hence it must neces- 



* [An abstract of the discussions on the subject of Phlebenterism 

 is given in the Appendix, Note XV.] 



