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salpa, especially if he have before him one of the larger kinds, 

 for example, the Salpa maxima Africana. The outer part 

 of the long barrelshaped body forms, as in the Aseidians, a 

 tunic or sack, at each of the two ends of which there is a large 

 orifice. The animal swims with its fore- end first by taking up 

 water through the front orifice and letting it stream into the 

 hollow of its body, across which the gills are stretched like 

 a ribbon. As soon as the body is filled with water, the front 

 orifice closes, the muscular girdles that span the body contract, 

 and at one stroke drive the water out of the back orifice, thus 

 impelling the animal forward , which , one might say , moves 

 by swallowing. Near the hind-part of the body is noticed a 

 round reddish-brown organ , the intestinal-ball , which is led 

 to by a mouth- orifice situated at the bottom of the cavity con- 

 taining the gills. In front of the intestine lies the transparent 

 gourd-shaped heart, which, in this animal a remarkable fact- 

 contracts alternately in diverse directions, so that the circulation 

 of the blood is periodically reversed. 



The development of the Salpa is of great interest for natu- 

 ralists. The poet Chamisso , who was at the same time an 

 enthusiastic zoologist, observed during his journey round the 

 world that in the Salpae "'the daughter never resembled her 

 mother, but her grand-mother, " as he expressed himself; that 

 is, that in one species two different forms regularly alternated, 

 the first consisting of a chain of several salpae, while the se- 

 cond consisted of independent individuals. Later research has 

 entirely confirmed this " change of generation " in the salpae, 

 and discovered new details. In the Aquarium are frequently 

 to be found both chains and single salpae near together; the 

 first are often of considerable length, or strung into a wreath. 

 All the members of such a chain are exactly similar in struc- 

 ture, and develop into hermaphrodites. From their eggs, how- 

 ever , issue not chainsalpae but separate individuals , which 

 are distinguished from their parents not only by certain dif- 

 ferences of structure , but also by the fact that they never 

 produce eggs. Instead they generate, on a special germ-stock 

 in the vicinity of the intestinal-ball, interior buds, which are 

 seen, even at a very early stage, to be little chain-salpae, and 

 are born as such so soon as they attain a certain size. The 

 germ-stock produces several of these chains. Like the Pyrosoma 

 among the Aseidians, the Salpae also belong to the phospborent 

 animals, and it is from the intestinal -ball that the most brilliant 

 light radiates. 





