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-J- 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 arid BISCHOFP. 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-f-f-, 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. 

 f TIEDEMANN, Zeitschrift, vol. v. part 2, 1835. 



I Beitriige zur Kenntniss der Geschlechtsverhiiltnisse und der Samen-flussigkeit wirbelloserThiere. Berlin, 1 84 1 . 

 Elements of Physiology (Eng. ed.), part 6, 1841, p. 1478. 



|| Anatomical and Pathological Researches, 1844, p. 40. ^f 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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