FIRST DAY'S SITTING. 



18 



I never heard of these " ancient progenitors " of ours the 

 Ascidians till now. Will Mr. Darwin inform me what 

 Ascidians are ? 



Darwin. Ascidians, my Lord, are " invertebrate, herma- 

 phrodite, marine creatures permanently attached to a sup- 

 port. They hardly appear like animals, and consist of a 

 simple, tough, leathery sac, with two small projecting 

 orifices. . . They have recently been placed by some natu- 

 ralists among the Yermes or worms. Their larvse some- 

 what resemble tadpoles in shape, and have the power of 

 swimming freely about." (Vol. i. p. 205.) 



Homo. Mr. Darwin, my Lord, has not supplied us with 

 an engraving of an Ascidian in his book, but here is one 

 which I have been allowel to copy from Professor Huxley's 

 " Introduction to the Classification of Animals." The Pro- 

 fessor says, " They look very much like double-necked jars 

 At first sight you might hardly suspect the animal nature 

 of one of these organisms, when freshly taken from the sea ; 

 but if you touch it, the stream of water which it squirts 



out of each aperture reveals the 

 existence of a great contractile 

 power within." Of the two 

 apertures, A serves as a mouth ; 

 B is the anal aperture, and c the 

 base of attachment, by which 

 it fastens itself to a bit of sea- 

 weed or to a rock. This is 

 called a "Solitary Ascidian," 

 because it exists by itself; 

 others are called "Social," 

 " Aggregate," or " Compound 



Ascidians," because they exist in groups, a number of them 

 being united into a mass. 



