288 EAMBLES OF A NATURALIST. 



liquid of the general cavity is subjected to the respi- 

 ratory action, quite as much as the blood itself.* 



Hitherto I had constantly seen the skin alone 

 performing this function. The air exerted its action 

 on the liquid to which I refer solely by means of the 

 integuments, either of the whole body or of some 

 portion of it which moreover served other purposes. 

 No animal was known which possessed special organs 

 for subjecting the chyle and the lymph to the respi- 

 ratory action; and consequently the observations 

 which I made on the Branchellion afforded me ample 

 materials for thought. 



The lateral appendages of this animal are not 

 perfectly similar, some are thin and laminated 

 throughout their whole extent, others, to the number 

 of about two and twenty, are regularly partitioned and 

 arranged in pairs, having at their base a hemi- 

 spherical and semi-transparent enlargement. In each 

 of these protuberances (mamelons) I discovered a 

 kind of sac (ampulla), which regularly dilated and 

 contracted in the same manner as a heart. Such is 

 in effect the nature of this organ, and the liquid 

 which it encloses is the blood of the animal. This 

 blood appeared, however, in healthy individuals, to 

 be tinged with a fine brownish-red colour, whilst the 

 liquid circulating in the appendages themselves ap- 



* These facts and the consequences deducible from them, have 

 met with considerable opposition. I have, however, daily the 

 pleasure of finding that they are more and more thoroughly 

 confirmed, and often in the most conclusive manner, by observers 

 who believe that they are making new discoveries while they are 

 only repeating my observations. 



