47 8 



The Tunicates, or Ascidians 



solitary salpa, or female, and the chain salpa, or bisexual males. 

 The latter are united together in long bands, each individual 

 forming a link in the chain held together by spurs extending 

 from one to the next. From each solitary individual a long 

 process or cord grows out, this dividing to form the chain. Each 

 chain salpa produces male reproductive organs and each de- 



FIG. 285. Botryllus magnus Hitter. Part of colony. (After Ritter.) 



velops as well a single egg. The egg is developed within the 

 body attached by a sort of placenta, while the spermatozoa 

 are cast into the sea to fertilize other eggs. From each egg 

 develops the solitary salpa and from her buds the chain of 

 bisexual creatures. Dr. W. K. Brooks regards these as nursing 

 males, the real source of the egg being perhaps the solitary 

 female. Of this extraordinary arrangement the naturalist- 

 poet Chamisso, who first described it, said: "A salpa mother 

 is not like its daughter or its own mother, but resembles its 

 sister, its granddaughter, and its grandmother." But it is 

 misleading to apply such terms taken from the individualized 

 human relationship to the singular communal system developed 

 by these ultra-degenerate and strangely specialized Chordates. 



