fined together in cages.
Romanes relates the interesting fact that when a cobra is killed, its
mate is often found on the spot a day or two afterwards. Darwin cites
an instance of the pairing in spring of a Chinese species of lizard,
where the couples appear to have considerable fondness for one
another. If one is captured, the other drops from the tree to the
ground and allows itself to be caught, presumably from despair.[45]

A further development is reached by those animals among whom what has
well been called "the note of physical fondness" is first sounded. We
find the males playing with the female, wooing and caressing her, it
may be dancing with her. The love-play is often extraordinary,[46] as,
for instance, in the well-known case of the stickleback. Not only does
the male woo the female with passionate dances, but by means of its
own secretions it builds a nest in the river weeds. The males at this
season are transformed, glowing with brilliant colours, and literally
putting on a wedding garment of love. The stickleback is passionate,
polygamous and very jealous of rivals. His guardianship of the nest
and vigilance in protecting the young cannot be observed without
admiration.

It is certainly significant to find one of the earliest instances of
genuine parental affection exhibited by the male. This reversal of the
usual role of the sexes is common among fishes, among whom care of
offspring is very little developed. In some species the eggs are
carried about by the father--the male sea-horse, for instance, has a
pouch developed for this purpose; in other cases the male incubates,
or cares for the ova. Sometimes, however, it is the female who
performs this duty, but the known cases are few.[47] Some exceedingly
curious examples of male parental care occur among the amphibians. One
of the most interesting is that of the obstetric frog, where the male
helps to remove the eggs from the female, then twists them in the
coils around its hind legs and buries himself in the water, until the
incubation period is over and the tadpoles escape and relieve him of
his burden. In other species the croaking sacs of the males, which
were previously used for amatory callings, become enlarged to form
cradles for the young. There are also instances of the female
co-operating with the male in this care of offspring. Thus in the
Surinam toad the male spreads the ova on the back of the female, where
skin cavities form in which the t