136 SALAMANDRAD^E. 



foot. At this stage a double dorsal line of minute brown 

 spots may be seen. All these characters continue to be 

 hourly developed ; and in the state which is represented at 

 figures 4, 5, it quits its envelope, which has been continually 

 becoming elongated to accord with the changing form of 

 the embryo. On first issuing from the egg, it swims about, 

 says Rusconi, without apparent consciousness of any im- 

 pediments, striking against a leaf, or the sides of the vessel, 

 and immediately adhering by its holders to the substance 

 against which it happens to strike, and remains thus sus- 

 pended for a time, as if asleep; and then, without any 

 apparent excitement, swims off to another part. The 

 developement of the young Tadpole, for such it must now 

 be considered, progresses with considerable rapidity after 

 its exclusion from the egg. In a fortnight, or three weeks, 

 according to the temperature, it has acquired the condition 

 exhibited in figures 6, 7. The branchiae now offer one of 

 the most beautiful and elegant objects in nature, as well 

 as one of the most interesting. Observed even with the 

 naked eye, the leaf-like division of these organs present 

 a most pleasing subject of contemplation ; but viewed in 

 the microscope, the branchial circulation excites the great- 

 est delight and surprise. The blood, which has now be- 

 come red, ascends by the branchial arteries, and returns 

 by the veins after having undergone the necessary change 

 of decarbonization ; and the globules of the blood are seen 

 accelerated by momentary jerks through the vessels. The 

 transparent tail affords a beautiful example of the systemic 

 circulation, as the former organs do of the respiratory ; 

 and in both instances the transparency of the parts is such 

 as to present no obstacle to the view. The eyes have now 

 acquired their permanent character ; the mouth has become 

 terminal, and the anterior feet have acquired distinct digi- 



