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processes detach themselves from the oval body, and are 

 seen moving irregularly about ; whereas in salt water, the 

 medium in which they naturally exercise their function, 

 they remain adherent. It is probable that observers, not 

 being aware of this fact, have used fresh water as a medium 

 in making their microscopic researches. KoUiker also 

 regarded some of these bodies as nucleated ; an opinion 

 which Dr. Burnett attributed to an optical illusion, pro- 

 duced by a cavity such as is found at one end in the Sper- 

 matozoa of the Lobster. In that of Pilumnus a similar 

 nucleated appearance is produced by a thin membrane, 

 often seen around one of the ray-like processes, which 

 refracts the light and produces this effect. 



Dr. Burnett exhibited a number of round, fleshy bodies, 

 taken from a sheep, in which animal they frequently fill 

 the entire space between the kidneys and the anus. 



He was of opinion that they are vascular sanguineous glands, 

 analogous to the Thymus, and Thyroid, and the Supra-renal 

 capsules, and like them perform some function connected with 

 the regeneration of the blood. Their direct connection with the 

 system is simply vascular, and their internal structure is quite 

 like that of the Supra-renal capsules. They are about as large 

 as a wild cherry. As to their origin, he thought them the remains 

 of an accidental embryonic structure ; in other words, blastodermic 

 remains. This view he thought the correct one, from the fact, 

 that Goodsir (Philos. Trans. 1846) has shown that these Supra- 

 renal bodies, and in fact the other organs of this nature, are 

 embryonic remains of the blastodermic membrane. 



Dr. Burnett thought that these bodies situated about the kid- 

 ney might, and probably do, have the same origin ; which view 

 would also be supported by their similar structure, and the fact 

 that they are nearly always seen in young animals alone. He 

 considered the subject an interesting one in connection with the 

 embryonic function of this class of organs, as aiding the forma- 

 tion of blood, and a nutritive material. 



Dr. Jackson said, that he had recently had an opportunity 



