REPTILIA. - The spermatozoa of the rep tilia possess the same shape as those of birds ; that is to say, an oblong cylindrical body, and a very fine hair-like tail.
No great differences present themselves in the form of these elements aniong the rep tilia with scales. Lizards, snakes, and tor toises uniformly possess, like most birds, a simple and straight body Cfig. 338.), which, however, is occasionally rather pointed towards the anterior part. This occurs, for instance, in the snakes. The only difference consists in the difference of breadth of body and tail. In the snakes (Coluber), in which the formation, which is assumcd to be seated on the body lengthwise, and which is said to be bent in a zig-zig manner to the right and left. It is true that this fibre is frequently only seen to rise on one side of the sperma tozoon, and in a shape which would encourage the conjecture just now alluded to (fig.340.); spermatozoa measure about the length of the body amounts to only -au."' ; in the lizards (Lacerta), on the other hand, in which the spermatozoa are smaller (T316"'--61-6"/) about a,"'.
The differences of the form of the sperma tozoa are however much greater in the group of the Batrachia, which likewise distinguish them selves in other respects by various deviating circumstances. A staffilike body with a very thin and proportionately short tail charac terise the spermatozoa of Rana and Bufo (fig. 339.). The length of the spermatozoa here amounts to about ii,'"-47,6"/, of which the body occupies more than the anterior third. Among the Salamanders the body is likewise cylindrical, but much longer (116'"), bent in the shape of a sabre, and thickest at its pos terior end.* Towards the anterior part it becomes gradually thinner, and (in Salamandra at least) furnished at the point with a very small globular knob. The tail is likewise of a considerable length. In the anterior part, which passes into the body, it possesses a not inconsiderable thickness. Towards the posterior part it becomes finer and thinner, until at last it can only be traced with diffi culty. The end of the tail is, however, not straight, nor curved like the anterior part, but turned up in a remarkable manner, and wound in very numerous narrow spirals round the commencing part of the tail, and even round the body. At least so we may ex plain the peculiar structure of the spermatozoa of Salamandra, and in this we agree with V. Siebold.t Others, especially French na
turalists, as, for instance, Pouchet, merely suppose the slender fibre, which is so twisted round, to be the contour of a ridge-like but in other cases the twistings are so distinct that they are not to be denied. We are of opinion that, whenever the tail has been lying only on one side of the spermatozoon, a partial twisting off' has taken place. This notched appearance may be attributed to the tail fibre retaining its spiral twistings. It is, however, remarkable that the tail never moves further from the trunk of the body, constantly main taining only a certain distance froni it. We do not venture to decide the cause of this, yet we cannot see in it a positive proof of the correct ness of Pouchet's view.
" The length of the spermatozoa is very con siderable. From the anterior point of the body down to the region where the tail bends itself, they measure in the Salamander 71.6-"', in Triton even -k"'. The spermatozoa of the Proteus seem to possess a still greater length, according to an iinperfect statement of Valentin.* The spermatozoa in Bombinator igneus (fig. 341.) are of a structure quite similar to those of the Salamander, only smaller. The body of the former is staff-shaped, tolerably long, and getting thinner towards both ends. The point is again rather enlarged, and flat tened. The posterior end is continued into the tail, which latter is tolerably thick, and almost straight at its commencement. It gradually, however, assumes a very thin appearance, becoming a very attenuated hair-like ap pendix, which exhibits the same spiral wind ings that occur among the Salamanders. The length of the spermatozoa, as far down as where the tail bends itself, amounts to zio-"'— Another very singular form of spermatozoa is met with in Pelobates fuscus. The sperma tozoa measure A.m. There is no boundary perceptible between the body and tail part, but one half of the spermatozoon distinguishes itself from the other by a considerable thick ness. Both, however, gradually pass into one another. The thicker part exhibits from its commencement a number (generally eight) of spiral windings, which increase in size towards the anterior free end (fig.342.). The anterior the cell of developement continue for a long time adhering to the body of the spermatozoa, generally in the centre, exhibiting the appear ance of a comb-like appendix of a variable shape and size.