MEDUSA BIFIDA. 117 



was liberated on the 26th ; and at the same date, a tenth likewise clasp- 

 ing, seemed nearly mature, while this last yet remained in its place, 

 fig. 15, a. An eleventh, only partially developed, fig. 15, b, appeared 

 rather towards one side, which could not be seen distinctly without the 

 microscope. Several tentacular organs, supposed to be those of the origi- 

 nal hydra, were now in view, when the subject with the two animals was 

 delineated on February 26. 



But these two animals remained so long in the same position, that I 

 concluded some unnatural incorporation with the basis or sustaining sub- 

 stance, c, had certainly ensued, nor, that it might have been so, is difficult 

 to be understood, considering the constant evolution and ready adhesion of 

 living matter in such products. I daily expected their liberation, how- 

 ever, as the basis was firmly fixed, and extending on the watch-glass on 

 the 6th of March, and was still more evidently a hydra. 



On the 10th of March, the clasping of the tenth was alone visible ; 

 the eleventh had disappeared ; and in a day or two its companion, the 

 tenth, disappeared also, without liberation, that I could discover. 



Thus the daily progress of this subject, apparently a formation on the 

 disc of the suspended hydra, had been uninterruptedly followed from the 

 14th of February until the 12th of March, or nearly four weeks. 



Ten or eleven days after separation by the sharp-pointed scissors from 

 the side of the vessel, while Medusse were coming to maturity, and escap- 

 ing from the one extremity of the subject, the probability of its basis, the 

 smooth fleshy slice, proving a hydra, was ratified by the partial protrusion 

 of tentacula. The fact was verified by its subsequent adhesion and diffu- 

 sion on the watch-glass ; nor could any doubt possibly remain when, on 

 the 25th of March, being entirely free of the Medusae, its long silky-look- 

 ing tentacula were waving in the water. Further, its nature was unequi- 

 vocally demonstrated by the germination of a young hydra from its body 

 a month later ; and in May, another descendant of one or other of the two 

 had established itself independently. 



From this detail it is obvious, that the progress of the Medusae to ma- 

 turity is progressive, and that a considerable interval, perhaps a whole 

 month, may elapse between the liberation of the first and of the last. 



