Thus we have seen that the arrangements under which leaves are shed are exactly repeated in the case of fruits, and that it is by no means needful that the object to be detached should be dead or dying. It may perhaps surprise you to be told that sometimes appendages are shed which have by no means accomplished their prospective work. Some plants shed their flowers and do this deliberately, having made their arrangements for a step which is apparently suicidal. In reality it is not suicidal, nor is it one of limitation of population, but simply of preferential employment of capital. The potato gives a good example of this. Every spring you may see on the heads of this plant beautiful flowers produced, which are destined in the course of another week to be only flowerless foot-stalks. The flowers break off at a pre-existing joint, just as leaves are shed. The influence which causes them to fall is inability to attract sap, in consequence of inability to proceed to the further stage of producing fruit. The young tubers underground make such overpowering demands upon the sap-furnishing capabilities of the roots that the flowers cannot obtain sufficient for their seed forming. Thus they at once die: if not obviously, at any rate practically, and detachment follows as a natural result. It is a case of competitive growth and the tubers win. After a time the plant will in the course of inheritance learn that it is useless to produce flowers, will give up the attempt; indeed, many varieties have already done so to a considerable extent. No better instance could perhaps be given of the law which goes through all animated Nature that activity is almost essential to continuance of life, whether in individuals or their parts. * * * * * THE OLDEST FOSSILS (Lingula).--It is a noteworthy fact that these, the oldest fossil animals known, belong to species by no means low in the scale. Yet every trace of the many millions which must have preceded them, and have gradually led up to their development, have perished. The period of time which must have elapsed subsequent to the advent of life upon the planet and the development of the lingula mollusc was probably quite as long as that which has passed since the lingula left its shell in the mud of the Portmadoc slate. The oldest fossils which are known are found in the lower Cambrian rocks. They are small oval shells, which were, during life, the protection of small soft-bodied sea animals of highly complex structure: they had red blood. Their descendants are still found in great numbers burrowing in sand on the shores of tropical oceans. They have received the name of Lingula, and have in turn conferred that name on certain hard rocks in which their shells occur in abundance, the “Lingula flags” of Wales (RAY LANKESTER). * * * * *