146 ZOOPHYTES. 



corpuscules, altogether resembling a bag of small shot under the microscope. 

 Some vesicles contained 24 at least. — Plate XXII. fig. 6. 



About 50 planules issued from the vesicles on the eighth of July, the 

 specimens having been procured on the day proceeding. These animals 

 were nearly a third of a line in length ; the body plump, approaching ro- 

 tundity, somewhat flattened below, of a smooth uniform aspect, and darker 

 in colour than straw-yellow. In course of their escape, they were ob- 

 viously suspended from various parts of the specimen by an invisible thread ; 

 but when reaching any solid surface, they advanced with an equal, gliding 

 motion, resembling that of Planarise. The observer could not associate 

 them with any other genus in the St/stema Naturce. No external organs 

 could be detected by the most careful microscopical inspection. They 

 assumed various forms, according to circumstances, and, as afterwards 

 established, these were modified also, according to the period of their ex- 

 istence. — Fig. 9. 



Many planulse continued quitting the vesicles from the 8th until the 

 12th of July. They spread on the bottom, and crowded together on the 

 sides of their vessels. Numerous dark green, thick, obtuse spines were 

 rising from spots on the bottom, on the 14th of the month. Several were 

 enlarging as buds next day, which had developed as a hydra from some 

 others of them. 



In the course of their progress, the spine is dark green, thick and ob- 

 tuse ; in further advance, the summit, enlarging, exhibits the hydra as 

 a green bud within its cell, the spine becoming the sustaining stalk ; 

 also the green colour of the stem, shows a central pith, contained in a 

 sheath of considerable width. — Figs. 10, 11. 



A nascent hydra had 16 rather long and slender muricate tentacula ; 

 the orifice of the cell was somewhat oblique. 



Prolific specimens having been committed to a vessel on the 10th of 

 the month, were withdrawn on the 14th. Numerous planula) quitting the 

 vesicles congregated at the bottom, and now at least 60 spines had rose, 

 that is, in four days from the time of their leaving the vesicles. But 

 farther progress was slow. No second hydra had been generated against 



