296 SEA-SIDE STUDIES. 



the globules of food are seen oscillating to and from the 

 cavities into the pear-shaped processes. I was com- 

 pletely puzzled what to consider this animal, until I 

 saw a tadpole embryo escape from it, and swim away, 

 followed by several others ; and then I knew an Asci- 

 dian of some kind was before me. 



A tadpole ? Well, that is a figure of speech. The 

 embryo of the Ascidian is more like a tadpole than 

 anything else ; and totally unlike its parent, not only 

 in possessing a good long tail, but in being able to 

 swim vigorously through the water in wliich the parent 

 is immovable. In the interior of the round body 

 which surmounts this tail, a mass of yellowish granules 

 (the vitellus) is observed, which extends some way 

 down the axis of the tail. The transparent membrane 

 smTounding the granular mass enlarges. The mass 

 develops three processes, which act as suckers, where- 

 with the animal finally fixes itself for life. The tail 

 then becomes absorbed, as in the tadpole.'"' The viscera 

 appear ; the envelope increases, and finally becomes the 

 general basis out of which, or in which, an immense 

 number of Ascidians are developed by the process of 

 " budding ; " so that from this one tadpole embryo 

 there arises a whole colony of animals, from which in 

 turn solitary tadpoles will issue, each of which will 

 produce its colony. Imagine a tadpole to be trans- 

 formed into a mature frog, this frog to swell liis skin 



* Some writers describe this disappearance of the tail as a fission, 

 the tail dropping off, I have not observed this. The enveloping mem- 

 brane, as it enlarged, included the tail within it ; and the absorption 

 took place within the sac thus formed. 



