FLUSTRA. 21 



cula or gemmules, of a fine orange colour, occupying the cells. They ap- 

 pear at different seasons of the year, January, February, March, Septem- 

 ber, October, one in each ; fig. 6. An irregular broad coloured belt, 

 extending across the leaf, is frequently formed by them; and they are 

 sometimes in such profusion, that a whole leaf, or even an entire specimen, 

 appears orange from their multitude. On one occasion, a number of spe- 

 cimens of the Flustra occurred in September, chiefly of yellow straw 

 colour, which is the more common hue. But among them some had an 

 orange tinge, which was derived from the thousands of deep orange gem- 

 mules occupying the cells. 



These gemmules have an intimate resemblance to those already de- 

 scribed in the present section. They are discharged from the cells as be- 

 girt by cilia, Plate V., fig. 6 ; but under corresponding irregularity of 

 shape and motions, fig. 7. When their activity ceases, and they are 

 about to become motionless, they seem to have a disposition for clustering 

 together, which renders the assemblage rather confused for inspection, nor 

 can solitary adhering individuals be readily found ; figs. 8, 9. — As a yellow 

 nucleus forms in the centre of the stationary gemmule, one extremity ex- 

 tends as a peak, tig. 10 : — which, in rising vertically, forms the originating 

 leaf.— Fig. 11. 



About twelve days subsequent to its escaping from the cell, the gem- 

 mule develops a Flustra with eight or ten tentacula, fig. 12 ; whose posi- 

 tion and proportions are exposed sufficiently in the enlarged representa- 

 tion. — Fig. 13. 



The date of production of the corpusculum or gemmule, the progress 

 of evolution, and permanence of the original hydra, founding the future 

 specimen, seem partly dependent on adventitious circumstances. 



I have not found observations on these facts, attended with equal 

 facility as in the preceding two species. 



Plate V. Fig. 1. Flustra truncata. 



2. Hydras protruded from the opposite sides of a leaf. 



3. Portion of the surface of a leaf with hydrse. 



4. Cells, as bounded in the leaf. 



5. Portion of a leaf with gemmules in the cells. 



