THE OVUM IN THE AMPHIBIA. 
171 
composition, as well also as of the fluid portion of the semen in which they move. 
Most of these inquiries have been well followed out by Wagner, Siebold, Muller, 
and more especially Kolliker, and more recently by Wagner and Leuckardt, from 
whose labours we have now some positive information which enables us to deduce 
a fair conclusion respecting their function, although a direct proof of its correctness 
is still to be supplied. Most observers now believe with Kolliker that the sperma- 
tozoa (still so called) are not independent living organisms, but are merely elemen- 
tary constituent parts of the male body, an opinion in which my own investigations 
lead me fully to coincide. This opinion, indeed, is not entirely new, as a like view 
was held by some observers at the beginning of the last century, when it was still 
questioned whether the spermatozoa are normal constituents of the semen. Dr* 
Drake*, in his ‘^New System of Anatomy,” while acknowledging that he had seen 
the seminal animalcules, and combating on the one hand the theory of Leewen- 
HOEK respecting them, and on the other the view that had previously been held with 
regard to the ovum, doubted their separate organization, and suggested that they 
“ may be nothing more than some large particles of mixed fluid, whose motions and 
different figure the microscope discovers to our eyes,” &c. G. Treviranus-I- more 
recently held a similar opinion, that they are not independent animals, but are analo- 
gous in their structure and properties to particles in the pollen of plants, and that 
their motion is of the kind discovered by Robert Brown in vegetables. Kolliker;!;, 
however, first distinctly referred them to a class of known organic constituents of the 
living body, the vibratile cilia, a view which had previously been discussed and in- 
clined to by Muller §. 
But however much our knowledge has become settled in regard to the nature of 
the spermatic bodies themselves, and their mode of development, their relation to 
the fluid portion of the semen in which they are contained is still a matter of doubt. 
H. Goodsir|| regards certain albuminous flakes in the fluid portions of the semen of 
Crustacea as the debris of dissolved cells, and as the source of nourishment and deve- 
lopment of the spermatozoa ; while a more recent observer. Dr. Kirkes^, regards the 
spermatozoa as the elaborators of the fluid, and the conveyers of it to the ovum at 
the time of impregnation. This latter supposition was originally advocated by Wag- 
ner, Valentine and Bischoff. But two of these observers have recently changed 
their views**, and now regard the fluid portion as only of secondary importance in 
impregnation, and the spermatic bodies as of essential. This view, as Wagner 
states'i''|~, is founded chiefly on the fact that in some of the invertebrata the whole mass 
* New System of Anatomy, by James Drake, M.D., F.R.S. vol. i. p. 352, 1707. 
t Tiedemann, Zeitschrift, vol. v. part 2, 1835. 
+ Beitrage zurKenntniss der Geschlechtsverhaltnisse und derSamen-flussigkeitwirbelloserThiere. Berlin, 1841. 
§ Elements of Physiology (Eng. ed.), part 6, 1841, p. 1478. 
11 Anatomical and Pathological Researches, 1844, p. 40. ^ Handbook of Physiology, 1848, p. 610. 
** Bischoff in Muller’s Archiv, 1847. Wagner in Article " Semen,” Cyclopaedia of Anatomy and Physi- 
ology, part xxxvi. January 1849. ft Loc. cit. p. 507. 
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