In terrestrial animals the organ of sight is furnished with glands by which a fluid is secreted, in order that the surface of the cornea may be kept perfectly clean. This fluid forms a wash which is passed over the eye by what is called the nictitating membrane.

But in the fish this apparatus does not exist, because it is unnecessary.

The element in which the animal lives performs the office of keeping the organs perfectly free from any substances which might impede the entrance of the rays of light.

If we now turn our attention to the instincts of fishes we shall perceive much that is calculated to point out the same Divine wisdom and foresight which are manifested in their organization. Without entering upon any discussion as to the nature of that marvellous power which we call "instinct," we shall merely refer generally to one of the most striking instances of its exercise in the creatures we are now consideringthat by which fishes are directed in the process of reproduction.

In order to the vivifying of fish-eggs, or spawn, certain conditions are indispensable which could not be attained in deep water, such as a certain degree of exposure to light, warmth, and the influence of the atmosphere. To accomplish this end there is an instinct implanted precisely adapted to the object in view. Directed by this unerring impulse, fishes at the breeding season betake themselves to such stations as are best suited to the continuance of their species. The herring, for example, frequents the comparatively shallow waters of the coast, and the salmon enters the rivers from the sea, and proceeds to shallow parts of the

streams, where the conditions necessary to the fruitfulness of its spawn can be obtained.

One of the most highly curious illustrations of the precision with which instinct in fishes has been observed to act is furnished in the case of the butterfly blenny, in itself one of the most beautiful of British fishes.

Mr. Ross, of Topsham, an excellent marine zoologist, says of the blenny

"A specimen of the fish was brought to me on the 3rd of June. On placing it in a glass vessel of sea water, it appeared perfectly quiet for some hours, but at length became restless and made frequent attempts to

throw itself out of the water. It then occurred to me that on a former occasion, when by the sea-side, I had a blenny, which regularly passed a portion of its time on a stone; I therefore placed one in the glass. The blenny immediately leaped on it completely out of the water. It therefore appears that these changes are necessary to its existence. On going to the front of the house I perceived that it was near low water. Knowing that it would flow till ten o'clock that night, I watched the movements of my little captive, and as the clock struck had the gratification of seeing it plunge again into its natural element. It has now been more than five months in my possession, and has proved throughout that period a regular and correct tide-indicator. I was well aware that these fish are constantly left by the receding tide on the rocks, remaining concealed in small basins or holes, under the weed, till the returning flood; still I was not prepared to see a fish voluntarily quit the water, and pass so large a portion of its existence in a different element, and by instinct alone time its change of position so exactly."

Phys'-ics, the science of physics deals | E-mit'-ted, sent or passed out.

specially with the general pro-
perties of bodies and their
mutual actions.

Centre of gravity, the point about which
the parts of a body gravitate
and exactly balance each other.
Specific gravity, the weight of a body

compared with another of equal bulk, the latter being specified or taken as a standard. Water is the ordinary standard. Den-tic-u-la-ted, having small teeth.

Lu'-bri-cate, to make smooth and slip

pery.

A-nal'-o-gous, bearing resemblance or
proportion to, similar to.
I-rid-es'-cent, coloured like a rainbow.
A-dap-ta'-tion, suitableness for, fitness.
Cor'-nea, the strong horny membrane
at the front of the eye through
which the rays of light pass.
Nic-ti-ta'-ting mem-brane, a fold of skin
which passes over and protects

the eye.

NOT LOST, BUT GONE BEFORE.-PART I.

"I WONDER What becomes of the Frog, when he climbs up out of this world, and disappears, so that we do not see even his shadow, till, plop! he is among us again, when we least expect him. Does anybody know where he goes to? Tell me, somebody, pray!"

Thus chattered the Grub of a Dragonfly, as he darted about with his numerous companions, in and out among the plants at the bottom of the water, in search of prey.

The water formed a beautiful pond in the centre of a wood. Stately trees grew around it, and reflected themselves on its surface, as on a polished mirror; and the bulrushes and forget-me-nots which fringed its sides, seemed to have a twofold life, so perfect was their image below.

"Who cares what the Frog does ?" answered one of those who overheard the Grub's inquiry; "what is it to us?"

"Look out for food for yourself," cried another, "and let other people's business alone."

"But I have a curiosity on the subject," expostulated the first speaker. I can see all of you when you pass by me among the plants in the water here, and when I don't see you any longer, I know you have gone further on. But I followed a Frog just now as he went upwards, and all at once he went to the side of the water, and then began to disappear, and presently he was gone. Did he leave this world, do you think? And what can there be beyond?"

"You idle, talkative fellow," cried another, shooting by as he spoke, "attend to the world you are in, and

·

leave the beyond,' if there is a 'beyond,' to those that are there. See what a morsel you have missed, with your wonderings about nothing." So saying, the saucy speaker seized an insect which was flitting right in front of his friend.

The curiosity of the Grub was a little checked by these and similar remarks, and he resumed his employment of chasing prey for a time.

But, do what he would, he could not help thinking of the curious disappearance of the Frog, and presently began to tease his neighbours about it again, What becomes of the Frog when he leaves this world? being the burden of his inquiry.

The Minnows eyed him askance, and passed on without speaking, for they knew no more than he did of the matter, and yet were loth to proclaim their ignorance; and the Eels wriggled away in the mud out of hearing, for they could not bear to be disturbed.

The Grub got impatient, but he succeeded in inspiring several of his tribe with some of his own curiosity, and then went scrambling about in all directions with his followers, asking the same unreasonable questions of all the creatures he met.

Suddenly there was a heavy splash in the water, and a large yellow Frog swam down to the bottom among the grubs.

"Ask the Frog himself," suggested a Minnow, as he darted by overhead, with a mischievous glance of his eye. And very good advice it seemed to be, only the thing was much easier said than done. For the Frog was a dignified sort of personage, of whom the smaller inhabitants of the water stood a good deal in awe. It required no common amount of assurance to