Microscopical Essays. 41^ 



Fig. 12, Plate XXL a polype that has {'wallowed a fmall 

 and taken the fhape thereof. 



Of the Generation of the Hydr.e. 



As the hydra fufca and the hydra grifea are .confiderably larger 

 than the hydra viridis, it is more eafy to obferve the manner of 

 their producing their young. It is upon thefe, therefore, that 

 moil of the observations here recited have been made. If one of 

 them be examined in fummer, when the animals are moft active 

 and more particularly prepared for propagation, it will be found 

 to burgeon forth from it's fides feveral little tubercles, or knobs, 

 which grow larger and larger every day ; after two or three days 

 infpeclion, what at fir ft. appeared but a fmall excrefcence, takes 

 the figure of a fmall animal, entirely refembling it's parent. 



When a young polype firft begins to fhoot, the excrefcence 

 terminates in a point as at e, Fig. 24, Plate XXIV. B, fo that it 

 is rather of a conical figure, and of a deeper colour than that of 

 the body. This cone foon becomes truncated, and in a little 

 time appears cylindrical. The arms then begin to fhoot from the 

 anterior end c i, Fig. 24, Plate XXIV. B. The tail adheres to 

 the body of the parent, but grows gradually fmall er, till at laft it 

 only adheres by a point b, Fig, 23, Plate XXIV. B; it is then 

 ready to be feparated ; for this purpofe the mother and young 

 ones fix themfelves to the glafs, or other fubftance upon which 

 they may be fituated. They have then only to give a hidden 

 jerk, and they are divided from each other. There are fome 

 trifling differences to be obferved now and then in their perform- 

 ing this operation, which it would be too tedious to enumerate 



here, 



