164 ZOOPHYTES. 



Neither the pulsation, nor the distribution of the sanguiferous fluid, 

 is quite regular, being occasionally and partially retarded or accelerated, 

 as in many of the lower animals. 



During my earlier observations on such singular productions, when 

 first beholding the eight radicles environing the nucleus, the fluid trans- 

 mitted through the channel of the attenuating neck, and the subsequent 

 alteration of their shape, I indulged some conjectures of their ultimate 

 conversion to perfect animals, forming a system of young ascidise around 

 the centre. Numerous dark specks were seen in the extremity beyond 

 the channel. Then the communication or neck connecting the parts dis- 

 appeared, but no orifices opened. Thus my conjectures proved fallacious. 



Increment. — A single animal is the origin of an entire colony of the 

 Botryllus, as a single animal is the origin of the Zoophytes proper. But 

 how shall we explain the formation of such an unwieldy mass as the spe- 

 cimen now under discussion ? 



The increment of this compound product seems to advance by a 

 second young ascidia pullulating from the side of the first, which conse- 

 quently ensues without the intervention of a spinula. — Fig. 22. 



Here the naturalist cannot fail to discover a remarkable coincidence 

 with the growth of the various genera of zoophytes, and that so strong, 

 that, were this the only feature of resemblance required, the two might be 

 almost identified. In the hydraoids, a second hydra developes beside the 

 first without the intervention of a planula ; in the ascidian genera, and in 

 the Alcyonium, a second hydra is evolved beside the original gemmule, 

 without a second elementary gemmule to form it. 



The Botryllus is next enlarged by a third ascidia pullulating from the 

 side of the second. — Fig. 23. 



Meantime the number of radicles augments, though I have not been 

 able to determine by what law. A nascent Botryllus, about eighty-one days 

 old, of gelatinous aspect, very prominent and distinct, resembled the longi- 

 tudinal half of an ovoid to the eye. It consisted of four ascidia;, surround- 

 ed by a common diffusion, wherein a number of radicles, perhaps as many 

 as corresponding to the complement of the whole form, were seated. Dark 

 particles were incorporated with the substance of the radicles, but no con- 



