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in the first individual which my friend Professor Valentine opened, 

 the organ corresponding and very similar to the ovary immediately 

 presented a difference (from the ovary) in its white contents. We 

 also saw indeed in those contents the most beautiful spermatozoa, 

 much resembling those of osseous fishes. Numerous other individuals 

 constantly presented themselves, either as males or females. 



" Regarding the Medusa, Von Siebold of Dantzic had already 

 mentioned that he had found "male individuals with spermatozoa in 

 Medusa aurita. In Nice I convinced myself with the greatest cer- 

 tainty in Pelagia, Aurelia, Cassiopeia, and a fourth genus, that these 

 Medusida are always of disjoined sex. The males, with their sper- 

 matozoa actively moving (even within the capsules of the testes), are 

 at the first glance to be distinguished from the females, whose ovaria 

 always contain ova in different stages of development*. 



" It is of especial interest to find that a disjunction of sex admits 

 of demonstration, even in the Polyps. One of my companions, Dr. 

 Erdl, (?) of Munich, found in Veretillum only female individuals in 

 one Polypary, and in others only males. He writes me that he has 

 afresh convinced himself of the same relation in Alcyonium, though 

 the specimen had been preserved in spirit ; and that among the MoU 

 lusca he has found similar sexual differences in Halyotis ; thus in the 

 Aspidobranchia of Cuvier. 



" I must here remark, that my earlier statements on the sperma- 

 tozoa of the Actinice are erroneous, since I regarded entirely peculiar 

 and remarkable capsules with long threads (situated even on the 

 prehensile arms) as spermatozoa. 



" My researches on the spermatozoa of cartilaginous fishes have 

 shown the remarkable fact that the individual genera of the Rays and 

 Sharks are distinguishable by the form of their spermatozoa. These 

 spermatozoa are for the most part spirally wound, as in birds of song. 

 Very remarkable is the structure of the testis ; which is constantly 

 connected with a largely developed and winding vas deferens. That 

 which Johann Miiller has described in the Rays as a peculiar gland 

 is nothing else than this vas deferens. The relations in form of the 

 male genital organs alternate much, as I shall show in a special and 

 more comprehensive work. 



" The facts here reported were not witnessed by myself alone, but 

 also by Professor Valentine of Bern, Dr. Peters of Berlin, and five 

 young zootomists, pupils of mine, who were all in Nice at the same 

 time as myself, and took a part in my observations." 



* I shall state these sexual relations in a special and detailed work on 

 the whole anatomy and physiology of the Medusce. 



December 24, 1839. 

 No meeting took place. 



