MOLLUSCA. 209 
heart was towards the front, and the downward back stream, 
instead of flowing out at the wound, was poured into the 
hinder end of the ventricle ; but when the current was re- 
versed part of the blood was driven for a time through the 
stump of the peduncle into the water: however, it soon 
staunched, and all the vital actions went on as before the 
separation, except that at the beginning of every pulsation 
there was a slight recoil. 
In one case where the circulation did not extend to an- 
other animal, one channel, and only one, was open in the 
peduncle, and in this a small current ran to and fro accord- 
ing to the direction of the impulse given by the heart- 
Some animals, which had probably been injured, but were 
still connected with other vigorous ones, seemed to be in 
course of absorption. One was observed in which the soft 
parts were so shrunk as to occupy a small part only of the 
tunic ; the.currents of its peduncle extended into this mass, 
but the heart, or motion of branchiae, was visible. Upon 
looking at the same the next day, the tunic was empty, the 
soft matter and circulation reaching only to the end of the 
peduncle. I also once noticed a flux and reflux of the blood 
in a creeping stem, where the current did not communicate 
with any animal. 
In some of the last mentioned particulars this Ascidia 
bears a resemblance to the Sertulariae, and, like them, 
it increases by sprouts: the two streams of the stem run 
through the bud before its organs are developed. No pro- 
per motion was seen in the particles of its blood, like that 
of the Sertulariae. 
In a sessile Ascidia, nearly half an inch in length, of 
which the coat was tco rough and opake to allow an inspec- 
