90 
Sanders^ on the Anatomy of the Generative 
be the ovary; tliis opinion was followed by Brandt and 
Ratzeburg,"^ who could find no trace of ova even under the 
microscope; also by Pre vost^f Verio ren_,{ and Paascli.§ Of 
those who adopted the opinion of Cuvier more or less com- 
pletely^ C. Gr. Carus || was the most conspicuous; he con- 
sidered the zoosperms which he saw in the follicles of the 
dichogamic gland to be the muscular fibres of their walls^ and 
those which he found in the duct to be strongly developed cilia. 
Van Beneden^ followed Cuvier and Carus; Pappenheim and 
Berthelin"^^ attempted to prove the same thing. Rud. Wagner 
at first believed the gland in question to be the testis_,tt but 
was converted to the opposite view by a letter from Carus^JJ 
but then he was considerably puzzled as to whence could 
have come the zoosperms which he saw abounding in it^ and 
which had before induced him to consider it as a testis. The 
first writer who maintained the double character of the gland 
was C. Vogt^ in a paper on the anatomy of Ancylus fluvia- 
tilis Stein II II confirmed his statement by investigations 
into the structure of the apparatus in Limnaus and Planorbis. 
Heinrich Meckel^^f^T in an elaborate paper,, describes each 
follicle of the gland as possessing two membranes^ one in- 
vaginated in the other, the inner producing zoosperms, and 
the ova being produced between the two ; the same arrange- 
ment occurs, according to him, in the ducts also. V. Sie- 
bold'^^^ entirely adopted this description; Semper,ttt 
Gegenbaur,t JJ and Moquin-Tandon,§§§ while conceding a 
double function to the gland^ denied the existence of the 
second membrane. The latest writer on the subject that 
I know of, Dr. Lawson,|| || || has attempted partially to return 
to the interpretation of Cuvier, inasmuch as he considers the 
prostate to be the testis. 
The fact of so many eminent writers taking such opposite 
and contradictory views of the same apparatus shows the 
obscurity of the subject. The object of this paper is to endea- 
vour to clear up the matter, as far as possible, by demonstrat- 
* ' Medizinische Zoologie/ 1827. 
t 'Mem. Soc. Phys. de Geneve/ v, 1833. 
J 'Responsio ad Questionem,' 1837. 
§ ' Wiegmann's Archiv,' 184:3'45, 
l| 'MuUer's Archiv/ 1835. % 'Aim. Sci. Nat./ v, 1836. 
C. 11, 1848. ft 'Lehrbucli/ 1834, 1835. 
Xt 'Wiegmann's Arcliiv/ 1835. §§ 'Miiller's Archiv/ 1841. 
nil Ibid., 1842. Ibid., 1844. 
• V. Siebold und Stannius' Lehrbuch/ 1845-48. 
ttt ' Siebold und Kolliker's Zeitschrift/ 1857. 
ttX ' Vergleich. Anat./ 1859. §§§ ' Mollusques de rrance.' 
11 111! 'Quart. Journ. Mic, Sc./ 1861 and 1863. 
