INDUSTRIAL PROGRESS DURING THE YEAR 1873. Ixxxvii 



Ocean contains. This faculty of the Baltic animals is by no 

 means indicated by calling them brackish-water animals ; on 

 the contrary, this expression carries our thoughts away from 

 one of their most remarkable peculiarities ; for animals which 

 can live not only in slightly, but also in strongly salt water, 

 are not brackish-water, but euryhallne animals. 



A very perfectly euryhaline animal is Hydrobia uIvcb. This 

 shell becomes developed in the slightly salt water near Goth- 

 land to the same size as in more than normally salt lakes on 

 the shore of the iSTorth Sea. He then concludes that because 

 the Baltic animals are eurythermal and euryhaline, they are 

 therefore capable of living both at small and great depths, 

 and of maintaining their ground throughout long geological 

 periods. 



An interesting j^hysiological fact has been discovered by 

 Professor Schneider, who finds that in the young or ammo- 

 coetes stage of the Lamprey eel, the thyroid gland performs 

 its functions during a long period of life, and exists in a highly 

 developed form. This is a remarkable fact, and is the only 

 case known of the gland's performing its function after the 

 young vertebrate has passed beyond its embryonic life. But 

 what this function is, Schneider does not state. It is well 

 known that the thyroid gland is an embryonic organ, proba- 

 bly, like the suprarenal capsule, of use to the embryo, but, 

 with the exception of the larval Petromyzon, or Lamprey, 

 of no use to the vertebrate animal after it is born. 



The singular mode of respiration in certain lizards, the 

 Psammodromis, has engaged the attention of M. J. JuUien. 

 He states that these animals do not swallow the air like the 

 Batrachians (toads and frogs), but when they respire, certain 

 muscular bundles traversing the lungs contract (as the heart 

 itself would do), the air is expelled, and after the contraction 

 re-enters the lungs by virtue of the elasticity of the thorax, 

 aided no doubt by the elevator muscles of the ribs. When, 

 he says, we observe one of these lizards breathing, the long- 

 est respiratory period is that of expiration, followed imme- 

 diately by a sudden inspiration. When a mammal respires, 

 the contrary is the case a long inspiration precedes a short- 

 er exj^iration. The respiration of these lizards therefore, in 

 his view, differs profoundly, both from an anatomical and a 

 physiological point of view, from that of Mammalia and 



