or THE SALP.'E. 41 



in theii" embryo state, beccmse also, there is no reason 

 for assmuing any other mode of association in the Salpa? 

 than that which originates in the foetal state, arid because 

 no certain observations tend to show, that the connexion 

 of these animals is ever restored after having been oncfe 

 dissolved, the impossibility of which is evident from the 

 structure of the organs of adhesion, as figured by Prof. 

 Eschricht. For he found in his specimens of Salpa 

 zonaria, which, all presented indubitable marks of the 

 rupture of a previous union, the fom* pedunculate bodies, 

 which as it is known, eventually form four solitary em- 

 bryos, just as Chamisso, and more lately Quoy, Gaimard, 

 and others have found them, and besides this, he ob- 

 served in the case of the Salpa cordiformis, that each em- 

 hryo constituting the embryo chain, while still inclosed in 

 the body of the mother, presented distinct traces of younger 

 solitary embryos ; Chamisso's observations, which bear all 

 the stamp of truth, are thus confirmed by those of several 

 others, as well as by the anatomical researches of Prof. 

 Eschricht, who, however, considers them as insufficient 

 for the foundation of such a theory as that of Chamisso 

 mentioned above, although that accurate observer himself 

 asserts, that he had traced the whole course of develop- 

 ment in one species, viz. in Salpa pinnata " hac unica 

 in specie, fatemur nos integrum metamorphoseos cy- 

 clum, hiatu nuUo, omnibus suis momentis absolutum 

 persecutos esse oculis." (/. c. p. 10.) Eor Prof. Escliricht 

 objects, that it does not appear from Chamisso's observa- 

 tions, that the associated Salpa produced from their 

 sohtary congeners, continue throughout to produce only 

 sohtary young ; it may be possible, that the associated 

 Salpa become detached after the birth of their first off"- 

 spring; may lose their organs of attachment; may assume 

 the sohtary form, and afterwards produce a later genera- 

 tion of (associated) embryos. And he goes on to observe 

 also, that it is not proved by Chamisso's observations, 

 that the solitary Salpce which produce chains of embryos, 

 and are thus the parents of associated individuals, are 



