212 



hier in einem See annähernd die alpinen C o r e g o n e n - E x t r e m e 

 vertreten finden: einmal das Gangfisch-Extrem im Albeli, sodann das 

 i^era-Extrem im Baichen. Wie möchte man da wohl den Beweis liefern, 

 dass das Albeli ein junger Baichen sei? 



Das Zuger Albeli laicht November — December in der Tiefe 

 des Sees. 



Der Fang geschieht mit Tiefestellnetzen. 



(Fortsetzung folgt.) 



2. Chamisso and the Discovery of Alternation of Generations. 



By W. K. Brooks, Associate in Biology and Director of the Chesapeake Zoological 

 Laboratory of the Johns Hopkins University, Baltimore Md., U. S. A. 



In the summer of 1875 I enjoyed, through the kindness of Mr. 

 Alex. Agassiz, the privilege of an introduction to the problems and 

 methods of marine zoological work, at his marine laboratory at New- 

 port R.J. As specimens of Salpa were very abundant I devoted myself, 

 at Mr. Agassiz' suggestion, and with his assistance, to the study of 

 their development, and my investigations led me to believe that the 

 eggs which undergo development inside the bodies of the chain-salpae 

 originate in an ovary which is contained in the solitary Salpa, and that 

 the latter is therefore a female, and the chain-salpa a male, 



I therefore gav the following brief statement of the life history of 

 Salpa (Bull. Mus. Comp. Zool. No. 14). 



The solitary Salpa, — female — , produces a chain of males by 

 budding, and discharges an e^^ into each of them before birth. 



These eggs are impregnated while the zooids of the chain are very 

 small and sexually immature, and they develop into females , which 

 give rise to other males by budding. 



Since both forms are the offspring of the female, the one by budding 

 and the other by true sexual reproduction, we have not an instance of 

 »alternation of generations«, but a very remarkable difference in the 

 form and mode of origin of the sexes. 



While I was writing my paper I received Kowalevsky's paper 

 on the development of Pj/rosowa (Zeitschr. f. wiss. Zool. 1875), and 

 found in this the statement that the eggs of Salpa arise in an ovary 

 which is contained in the body of the solitary Salpa, but he fails to see 

 that this makes the solitary Salpa, which he speakes of as the Salpen- 

 Amme, a female. 



As the animal in Avhich eggs first appear, as eggs, is certainly 

 their mother, the acceptance of my conclusion is unavoidable if my ob- 



