HYDRA. 91 



Other two specimens were next subjected to similar experiment, — 

 PI. XIV. fig. 3, a, and fig. 3, b, — ^both being on the convexity of the shell. 



The former, a, which is represented separately by fig. 4, was bisected 

 with very sharp scissors, on March 12. The stump is seen, fig. 5, as re- 

 maining in its place after bisection. 



In a fortnight, this stump had generated about sixteen long silky ten- 

 tacula, fig. 6 ; but neither extending so equally nor preserving such regu- 

 larity as shewn by specimens entire. However, they continued advancing, 

 and the stump to which they belonged became a complete animal ; when 

 it was accidentally lost, along with some of its neighbours, above a year 

 after the group had come under observation. 



So much for the under half. In regard to the upper half, severed 

 from fig. 4, that is fig. 3, a, bisected as already said on March 12, the 

 wound had healed when delineated with the original tentacula, on March 29, 

 fig. 7 ; enlarged, fig. 8. Thus two perfect animals resulted from the bisec- 

 tion of one. 



But this last, fig. 8, subsequently exposed some peculiarities. Its 

 tentacula were nearly but not completely obliterated. Several short, ob- 

 tuse prolongations, unlike originating tentacula, next appeared on the 6th 

 of May. The subject had undergone much alteration on May 25, then 

 consisting of many obtuse parts, as more distinctly seen when enlarged. — 

 Fig. 9. Farther alteration alike singular had ensued on the 5th of June, 

 fig. 10, at which time these anomalous parts extended as tentacular organs 

 of very irregular length and form. Some were long and slender like ge- 

 nuine tentacula ; others thicker and shorter : but there being a constant 

 tendency of nature to produce or to restore symmetry, the whole were 

 approaching the proper shape in 16 days, or on June 21. — Fig. 11. This 

 refined still farther, figs. 12, 13, as on August 21 and 29, when perfect 

 symmetry had been acquired. 



It still remained to be seen whether so great a mutilation as priva- 

 tion of half the body, which this subject had undergone, was now com- 

 pletely redintegrated, in as far as to carry on all the purposes of existence. 

 Time alone could prove it ; and the fact] was at length verified indubitably 

 by the gemmation of progeny from its side, and separating to enjoy inde- 



