Page:Proceedings of the Royal Society of London Vol 69.djvu/307

Rh taneously, or in succession. Naturally, it is the stronger plants which most frequently multiply thus, but plants of a smaller number of proto- phylls may branch in this way. One plant of a single protophyll was found with two tubers forming.

The occasional occurrence of branching in the strobilus might be interpreted as an indication that the ancestors of the plant were once more abundantly branched. But it would be possible to take the opposite view that such branching is a nascent feature, that it is a new feature in the phylogeny. Bertrand regarded Phylloglossum as a form reduced on account of its semi-aquatic mode of life. But it is necessary to point out that Phylloglossum is not a setni-aquatic ; Bertrand never had the advantage of seeing the plant in its native home. Phylloglossum, it is true, being a very small plant, can only grow whilst the surface soil is fairly moist, hence it forms a tuber and rests during the dry season. So far as I have seen, the plant grows rather better on a hill-top ; or, at any rate, it grows there at least as well as it does lower down on the slope, and I have never found it in an actual swamp. It grows well on a slope where water can never lodge. Its roots spread rather horizontally, and seldom far downwards in the ground, as though it objected to a waterlogged soil.

Whilst it is possible that evidence may yet be adduced that Phyllo- glossum in some measure owes its simplicity to reduction, there appears to be little evidence for this at present. On the other hand, it may yet prove that Phylloglossum is an exceedingly primi- tive plant, possibly the most primitive of existing Pteridophytes. We have an explanation ready to hand of this exceptional retention of ancient characters, namely, the annual renewal of the embryonic- stage in the formation of the protocorm. But however this may l>e decided, the relatively simple character of the gametophyte and the comparison of the mature sporophyte with the embryo of Lycopodium cernnniu are in favour of the view that Phylloglossum is the most primitive of existing Lycopodinse.

Von Erlanger, in his work on the development of Paludina, made known for the first time the existence, at an early stage of develop- ment, of a rudimentary kidney belonging to the original left side of