The Tunicates, or Ascidians 



471 



will consider that of one of the solitary forms, leaving the many 

 curious modifications to be noticed in connection with the 

 species in which they occur. This will be best, since these 



Fig 278. — Development of the larval Tunicate to the fixed condition. (From 

 Seeliger, per Parker & Haswell.) a, larva; b, intermediate stage; c, adult. 



forms show the relationship to the other vertebrates in the clear- 

 est manner. 



The egg undergoes a total segmentation and a regular gas- 

 trulation. Soon a tail appears, and under the microscope 

 the young embryo, which now begins its free life, appears much 



