by the red leaf of Acalypha as compared with another sun-plant— Passiflora—and from this he is led to consider (somewhat inconsequently perhaps since the Acalyyha was a sun plant) that a red coloration of the leaves of the undergrowth may possess the same biological significance as that of Red Algae — to enable arc to be made of the green light which filters through the leaves of the forest. A third observation worth nothing is as the so- called drip-tip, which as developed in this forest he considers has not the signifiance ascribed to it by Stahl in Java, the nature of the surface having more effect on drainage than this shape of the leaf. In this connection reference may be directed to a paper by L. S. Sedgwick who offers an ex- planation of the existence of acuminate apices in the 'Indian Forester '.
Prothallia of Lycopodium.
C. J. Chamberlain, Prothallia and Sporelings of three New Zealand Species. Botanical Gazette, Vol. LXIII, No. 1, pp. 50 — 64.
The author gives short resume of the literature of the subject, followed by notes on L. laterale, L. oolubile, and L. scraiosum, collected in New Zealand. He finds a green leafy prothallium, with protocorm developed, only in the first, which is a terestial species. The other two species are epiphytic, and the prothallia are subterranean, with no protocorm. He suggests that this differentiation occurs throughout the genus : and that the green leafy prothallium represents the original type, and that the change to the suprophytic subterranean type occurred in consequence of a delay in germination (some spores require from 6 to 8 years) which allowed only those spores that had reached some place of safety, i.e., had been buried, to produce plants.
E. A. Spressard gives (l.c. pp. 67—78) a very interesting account of the finding of prothallia of L. clavatrum, L. obscurum, L. annotinuv, and L. lucidulum, nearly all quite close together, in an open space near Marquette Michigan. They were found only on small knolls covered partly by Polytrichum and partly by a grass, or sometimes almost bare. He suggests as a reason for this that such spores as were carried and fell on these spots were first of all beaten into the ground by rain, then covered by the shifting sand, and finally conveyed to a favourable depth by percolating water. This theory worked well or guide to where to look for the prothallia. The piper establishes the fact that prothallia have been found in America, and announces the discovery of two new species of prothallia— L. obscurum and L. lucidulum.
Algae.
Hybrids of Spirogyra. — E. N, TranSEAU 1 . (" Hybrids among species of Spirogyra." American Naturalist, March-April 1919) has published a paper recording the results of his experiments on hybridization in species of Spirogyra, especially between S. communis and S. varians, and S. varians and S. porticulis. He finds that hybrid zygospores may be formed between species even though they have very different vegetative and spore characters. The nuclei of the gametes do not fuse until after the zygospore-wall matures. The form of zygospore is determined entirely by the female gamete. Filaments derived from hybrid zygospores show their hybrid character in the dimension of filament, character of sporiferous cell and the form of zygospore.
