THE PAST AND PRESENT OF THE CUTTLEFISHES. 95 



cavities, named ''branchial hearts" or "gill-hearts," which contract 

 in a rhythmical manner and correspond in function to the right side 

 of the human heart, in that they propel venous blood into the organs 

 of respiration. According to Huxley, these " branchial hearts " pul- 

 sate in Loligo media about sixty times per minute. The work of ex- 

 cretion, or the elimination of the waste materials produced by the 

 actions of existence, is effected in cuttlefish-existence, as in human 

 physiological history, by the organs of respiration and by the kidneys 

 or their representatives. The skin-surfaces, of importance as an 

 excretory apparatus in man, do not appear to be associated with the 

 elimination of waste materials in the cuttlefishes. The impure blood 

 gathered from all parts of the body is at last received by two main 

 or terminal veins, one for each gill. Each of these veins appears to 

 pass through a chamber or cavity which in turn opens into the cavity 

 of the mantle, whence the effete water of respiration is ejected by 

 the funnel. That part of each vein which lies within this cavity, and 

 which is bathed in the water the compartment contains, has a 

 glandular structure. Hence it becomes clear that, as the blood 

 traverses this glandular portion of the vein, certain waste matters are 

 removed from it, and transferred to the water of the mantle cavity 

 and thus got rid of. The glandular parts of these veins, in a word, 

 represent the kidneys of higher animals, and earthy matters contain- 

 ing phosphate of lime are found in the chambers traversed by the 

 veins in question. These mineral concretions have doubtless been 

 eliminated as waste materials from the blood. 



The gills, as already noted, number two in all cuttlefishes except 

 the pearly nautilus, and may demand a special notice. Each gill is 

 a conical organ, consisting essentially of a dense network of blood- 

 vessels, in which impure blood brought by the great veins is exposed 

 to the action of the oxygen contained in the water which is being 

 continually admitted to the gill-chambers. Each gill is contained 

 within a kind of chamber, to which water is admitted by the front 

 edge of the mantle-sac. This opening being closed by a valve 

 against the exit of the water, the forcible contraction of the body- 

 walls ejects the water, as previously described, from the "funnel." 

 The gills are themselves contractile, but they do not possess the 

 armament of minute vibratile processes or cilia^ so typical of the 

 gills of other Mollusca. The need for these cilia as organs provid- 

 ing for the circulation of water over the gill-surfaces is of course re- 

 moved, in view of the very perfect means existent in the cuttlefishes 

 for the renewal of the water used in breathing. As a living octopus 

 or other cuttlefish is watched, the movements of inspiration and ex- 

 piration are plainly indicated by the expansion and contraction of 

 the body -walls, and they imitate in a singularly exact fashion the 

 analogous movements of the highest animals. Observers have like- 



