44 
SPERMATOZOA. 
species of various classes of animals. It was his opinion that they 
formed the embryo, and that the female’s share in the work of pro- 
pagation was simply’the reception and nutrition of the male pro- 
duct. This view of LEEUWENHOECK’s as to the office of sperma- 
tozoa in propagation was afterwards entirely rejected: until, in our 
own century, Dumas maintained that they form in animals the 
foundation of the nervous system (the brain and spinal cord) : to « 
which view he was led by a certain resemblance of the first rudi- 
ment of the embryo (the so-called primitive streak) to a spermato- 
zoon (Dict. Classique d Histoire naturelle, T. vu. 1825. p. 221, 
article Génération, Annales des Sc. nat. xu. 1827. p. 443-454). 
But it is not founded on observation, and is moreover sufficiently 
refuted by the fact that some animals have spermatozoa closely 
resembling those of mammals, whilst their nervous system has a 
totally different form from theirs. 
According to WAGNER'S Investigations, these active molecules are 
formed in cells, singly or in bundles: from which, on bursting of 
the cell-wall, they are set free. In insects they are found as fine 
threads without a head, or thicker portion: but in most other 
creatures they consist of a thicker part, the head, and a very fine 
thread, or tail. The head is, in different animals, of a different 
shape. 
[The spermatozoon of the Batrachia has an extremely fine mem- 
brane attached to its tail in the direction of its axis and throughout 
its whole length by one of the sides, the other being free and wavy. 
Thus a delicate undulating border is formed. It was discovered by 
Amici and rightly described by him, and afterwards by Pouter. By 
others it was mistaken for a thread surrounding the tail with a loose 
spiral coil. Vid. J. N. Czermak, Zeitsch. f- wissensch. zool. B. 11. 
350-355, also von SIEBOLD, ibid. pp. 356-364. | 
The different memoirs and treatises upon this subject with whose history, as 
EHRENBERG says, whole volumes might be filled, are not noticed by us 
that we may not incur a diffuseness unsuitable to the limits of this manual. 
R. Wacner’s Lehrbuch der speziellen Zoologie, 2*° Auflage, Leipsig, 1843, 
8vo, s. 1O—-30 may be consulted with advantage. It gives a full account of 
the most important discoveries of the author and of other contemporary 
observers. [This work has been translated into English by Dr Willis. 
Comp. the later work of R. WAGNER and R. Leuckarr, Aricle Semen in 
Topv’s Cyclop. of Anat. and Physiol. Vol. Iv. p. 849.] 
