SOLITARY SALPS AND CHAIN SALPS 303 



out at the other without lacerating it ! However, on 

 one side of the packing-case-with-the-ends-knocked-out 

 there is a little soft mass of gut and a heart and other 

 tissue, often coloured red or blue. Floating among the 

 large salps we often find chains of smaller salps, the 

 individuals twenty or more in number being joined side 

 by side by means of a distinct band like that of the 

 Siamese, twins. These smaller salps may be as big as a 

 hazel-nut, and the chain or row of them is often two feet 

 long. These chains of living creatures look like unclasped 

 necklaces of crystal beads floating in the water. A very 

 interesting fact is that the " chain-salpae " are produced by 

 budding inside the large single salps. One may often 

 find the young chain coiled like a serpent within its 

 parent, and clearly visible through the latter's glass-like 

 body wall. It escapes when grown to a certain size, and 

 quietly floats away, feeding and growing. But the number 

 of individuals in the chain from twelve to fifty or more 

 (according to the species) does not increase after birth, 

 nor do they individually grow to be much more than a 

 quarter of the size of their parent when the chain breaks 

 up and they, too, float for a time as detached individuals. 

 The big solitary salps produce by internal budding 

 these chains of smaller salps differing so much in details 

 of shape from themselves as to have received special 

 names as separate species ; but they do not produce eggs. 

 On the contrary, each of the small individuals constituting 

 a chain of salps produces within it one egg ; and this, 

 when fertilised, grows within its parent to a fair size, and 

 is extruded or " born." Then, without passing through 

 any " tadpole phase," it increases in size and becomes a 

 solitary big salp, which in due time produces another 

 chain. So that there is an alternation of generations, the 

 chain-salps producing solitary salps and the solitary salps 

 producing chain-salps. This fact was observed and 



