30 ZOOPHYTES. 



gular that the intervals then became so much abbreviated, that while 60 

 days elapsed from the cleaving of the stalk to the evolution of the first re- 

 generated head, 90 betveeen the fall of the latter and evolution of the 

 second, and 143 from the fall of the second and evolution of the third, no 

 more than 14 days were occupied in the regeneration of the fourth. 



The embryo is often invisibly sundered in cleaving the stem. Two 

 vacant stalks, a and 3, were cleft down six and nine lines respectively. 

 What followed ? In 16 days a head slightly distorted was issuing from a, 

 the former, and one quite entire in 21 days from b, the latter. Neither 

 rose from the centre of the stalk ; but they originated individually from 

 one of the halves of the cleft, about three lines from the extremity. Each 

 regeneration became free of its half as it grew, and both proved symmetri- 

 cal ultimately. The head from a had 13 tentacula, that from b had 12. 

 Each head fell in eleven days. These heads, though on different stalks, 

 corresponded in position. The first regenerated head of «, adhering to one 

 side of the cleft, having fallen, another head, somewhat distorted, with 

 12 tentacula, issued from the opposite side of the cleft, 41 days subsequent 

 to the original cleaving. It will be recollected that each head first re- 

 generated had subsisted eleven days. Here the embryo had been undoubt- 

 edly sundered by the edge of the instrument. One half of the cleft of a 

 had exhibited a head with 13 tentacula in 16 days ; but the evolution of 

 what we may conjecture the other half of the sundered embryo was post- 

 poned during 41 days. 



The summit of a stalk having been cleft, on the 14th of February, 

 two perfect heads were produced on the 3d of March. But the embryo 

 had not eluded the edge of the instrument ; for, only 12 tentacula being 

 on one, and 10 on the other, the whole did not exceed the complement 

 belonging to a single hydra. 



The same may be said of the specimen above described, and repre- 

 sented PI. II. fig 13. 



Monstrosities. — If the wound be such as absolutely to preclude the 

 redintegration of the parts by the sanative energies of Nature, a real mon- 

 strosity may ensue, and this may appear either in excess or defect. The 

 subject of monstrosity is deeply interesting to physiologists ; they will ge- 



