In those species in which the embrace is of long duration the limbs of the male, usually the fore limbs (pleurodele newt, Ecaudata), rarely the hind limbs (a few American and European newts), according to the mode of amplexation, acquire a greater development, and are of ten armed with temporary horny excrescences which drop off after the pairing season.
During pairing he thrusts the tip of these organs into the seminal vesicles of the female and the eggs are fertilized as they pass out of the oviduct.
Owing to the smaller size of the male and the greater voracity of the female, the male makes his advances to his mate at the risk of his life and is not infrequently killed and eaten by her either before or after pairing has been effected.
Hares are remarkably prolific, pairing when scarcely a year old, and the female bringing forth several broods in the year, each consisting of from two to five leverets (from the Fr.
In the male, moreover, the pincers are caliper-like and toothed at the base, whereas in the female they are untoothed and only lightly curved at the tip. These differences suggest that the pincers aid in the pairing of the sexes.
The pairing time of the squirrel is from February to April; and after a period of gestation of about thirty days the female brings forth from three to nine young.
It seems to be fairly well established that in the meiotic phase there is a truequalitative division brought about by the pairing of the chromosomes during synapsis, and the subsequent separation of whole chromosomes to the daughter nuclei.
It has been suggested that synapsis may be connected with the early longitudinal splitting of the thread or with the pairing of the chromosomes, but it is possible that it may be connected with the transference of nucleolar substance to the nuclear thread.
The natural song of the canary is loud and clear; and in their native groves the males, especially during the pairing season, pour forth their song with such ardour as sometimes to burst the delicate vessels of the throat.
Taking each leaf of his series, with an assigned number of veins, he has determined the array of pairs of leaves which can be formed by pairing the chosen leaf with all others from its own tree in succession.