4G2 ANNUAL REC011D OF SCIENCE AND INDUSTRY. 



Various Physiological Adaptations of Fishes for Aerial Respira- 

 tion. 



M. Jobert, of Dijon, a French naturalist who has been 

 travelling in Brazil, has recently published a memoir in 

 which lie has called attention to some interesting modifica- 

 tions of several diverse organs or regions for the same phys- 

 iological purpose that is, aerial respiration. It is probably 

 generally known that although most fishes do not need any 

 more air than that which is furnished through the medium 

 of the w r ater to the gills, there are some which have peculiar 

 adaptations of certain parts for the direct respiration of air, 

 and which actually need access to the air, and die if totally 

 deprived of it. Such has lonsj been known to be the case 

 especially with certain Indian fishes. M. Jobert's studies 

 have been on some characteristic South American types, and 

 may be briefly summarized as follows: 



It was lon<? a^o shown that the air-bladder in certain 

 Characins of the genus JErythrinus^ and in Sudis or Ara- 

 paima was, in part, cellular or lung-like, but M. Jobert lias 

 demonstrated that, not only morphologically, but physiolog- 

 ically, is the air-bladder a lung in two species of Erythri- 

 nines, as well as in Arapaima. In the Erythrinines, the pos- 

 terior compartment of the bi-partite air-bladder is, at the 

 anterior region, copiously provided with blood-vessels, which 

 originate, not from the usual branch of the aorta, but from a 

 special vein through which venous blood is conveyed from 

 the intestine as well as the walls of the abdomen. "After 

 circulating through the rich plexus of blood-vessels in the air- 

 bladder, the blood is returned in a purified state directly to 

 the sinus venosus, or hindmost division of the heart, instead 

 of being taken into the portal vein, as is usually the case 

 with the returning current from the swim-bladder." In Ara- 

 paima gigas, it is the upper surface of the air-bladder that 

 is endowed with the proper amount of vascularity, and this 

 has, according to M. Jobert, the appearance of the lung of a 

 bird. 



In other fishes, it is a portion of the intestinal tract that is 

 specialized for purposes of aeration, and observations have 

 been made by Jobert on representatives of several groups 

 of the order of Nematognathi an order, typified by the 



