336 



BULLETIN OF THE 



to accept the view which has been generally held since the time of 

 Chamisso's famous paper ; that is, that Salpa presents an instance of 

 " alternation of generations." This view, in its most modern form, 

 may be stated as follows : " It is now a settled fact that the repro- 

 ductive organs are found only in the aggregated individuals of Salpa, 

 while the solitary individuals, which are produced from the fertilized 

 eggs have, in place of sexual organs, a bud-stolon, and reproduce in 

 the asexual manner exclusively, by the formation of buds. Male and 

 female organs are, so far as we yet know, united in the Salprj in one 

 individual. The Salpce are hermaphrodite." (Leuckart. Sulpa und 

 Verwandten, pp. 46 and 47.) When, however, we trace backward the 

 history of one of the individuals which compose a chain, and find that 

 the egg is present at all stages of growth, and has exactly the same 

 size and appearance as at the time when it is impregnated ; when we 

 find one organ after another disappearing until at last we have noth- 

 ing but a faint constriction in the wall of the tube, indicating what 

 is to become the animal, the conclusion seems irresistible, that the 

 animal, which as yet has no existence, cannot be the parent of the 

 egg which is already fully formed.* 



Fig. 34. 



Seven zooids from a fully developed chain, immediately before its discharge from the body of the 

 female ; the references are the same as in Fig. 33. 



* The development of 'the eggs in the body of one zooid, and their passage into 

 the body of another produced by budding from the first is not unusual among the 



