158 ZOOPHYTES. 



My expedient for diffusion of the growing Botryllus on the watch- 

 glass having succeeded, a thin transparent portion spread, unintercepted, 

 from the larger extremity. 



Herein were distributed a number of vessels resembling long grapes, 

 terminating channels from behind. A cluster of five terminated as many 

 channels, apparently connected with a common channel, originating in one 

 of the ascidia? on the leaf. — Fig. 5. 



Many other similar vessels, with their peculiar channels, were dispersed 

 throughout the transparent diffusion. Had the specimen been old and full 

 grown, I conclude that it would have presented an arrangement of the 

 sanguiferous sytem, corresponding to a section from one of large dimen- 

 sions, as represented Plate XXXVII. fig. 15. 



Numerous yellow particles, of equal size, and evidently suspended 

 in a transparent fluid, pass along the channels into the long grapes, and re- 

 turn after a brief interval. Their course is extremely irregular ; sometimes 

 many pass from the vessel slowly along the channels, or rush down like the 

 sand through the neck of a sand-glass. Then the current downwards is 

 interrupted for a minute or two, when a new current, flowing upwards, 

 carries the yellow globules along with it. 



This goes on at the same moment in many vessels and channels, while, 

 in some others, all is stationary and quiescent. 



Meantime a similar current is discovered within the body of the Asci- 

 dia, through the larger orifice at the summit. 



But both here and throughout the diffusion, the sides of the channels 

 were imperceptible. Nevertheless, that the currents were confined in 

 channels, is ascertained from the transit of the globules being invariably 

 continued within the same boundaries. Certain marks denoted the precise- 

 course followed by them. 



The visible discharge of these secret functions, so far withdrawn from 

 the gaze of mortals, is a most interesting spectacle. It shews the applica- 

 tion of those great and comprehensive general laws devised for the con- 

 servation of animal life. 



The flux and reflux of what must be deemed equivalent to the circu- 

 lation of the blood in the larger works of the creation, though quite evident 



