44 EXTRAORDINARY FACT. 



the water is expelled ; and it is supposed to receive 

 food from the currents of water, traversing the aerating 

 cavity, as in the ascidise. The stomach is covered 

 with rows of long filaments, regarded as analogous in 

 their office to the liver ; the intestinal canal terminates 

 near the posterior orifice, or that through which the 

 water is imbibed. 



The history of these animals is very obscure. Cuvier 

 states that sometimes the creature is seen completely 

 protruded from its investing tunic without appearing 

 to suffer ; and, according to M. de Chamisso, some 

 species live, under certain circumstances^, aggregated into 

 one mass, numbers of distinct individuals being united 

 together by suckers, and forming long chains, which 

 swim in concert, the arrangement of the chain varying 

 in each species. The union in this case is not organic, 

 still it is a curious circumstance : but what is more 

 remarkable is, that these aggregated salpse produce 

 beings of very different forms and habits to them- 

 selves, which live isolated ; and that these isolated 

 beings in turn produce aggregated salpse resembling 

 their parents, which again produce isolated creatures ; 

 alternate generations of animals of dissimilar form and 

 habits thus resulting from one origin. Cuvier, who 

 alludes to Chamisso's account, adds, " It is certain that 



