The Cereal Rusts

end of the sac a haustorial tube is developed, which passes through the micropyle, and then enlarges very much and sends out numerous branches which penetrate the funiculus and also the outer integument. The tube is occupied by an endosperm nucleus, which in the enlarged region outside of the micropyle becomes correspondingly enlarged and amoeboid in outline. There is also a short chalazal haustorium. The tapetal layer of the inner integument eventually becomes cutinized, and the vascular connections through the funiculus are imperfect, so that the embryo is fed through the haustoria, especially the prominent micropylar one. Such haustoria are common among the Sympetalae, but the micropylar ones are imbedded in the heavy integument and usually do not wander out of the ovule through the micropyle.-J. M. C. A parasitic alga on tea.-HUTCHISONN23 has studied the life-history of Cephaleuros virescens, the so-called "red rust" of tea. This remarkable alga is the greatest menace to the tea crop in northeastern India; and another observer is cited as stating that it is doing serious damage to mango trees in Bengal as a stem blight. This "blight" alga is one of the Chroolepidae, and attacks the leaves of the tea plant, completely piercing them; but the serious form of attack is upon the cortex of young stems. The alga occurs as orange-yellow, roughly circular patches on the upper surface of the host. It is propagated from these patches either by the discharge of zoospores under conditions that favor swimming, or by the breaking-off of the sporangium and its transportation bodily by the wind. The attack on young stems is intimately connected with their rough surface, all the young algal patches being found in the crevices of this surface. If the young shoot grows rapidly, it may outstrip the alga and "no permanent infection takes place;" but if the young shoot grows slowly, the alga is able to penetrate and destroy it.-J. M. C. The cereal rusts.-EVANS 24 has undertaken a detailed study of the histology of the "cereal rusts," that is, the species of Puccinia formerly included under P. graminis, P. rubigo-vera, and P. coronata, and more recently broken up into a greater number of species on the basis of both morphological and physiological characters. The investigation was begun at Cambridge in I903, at the suggestion of the late Professor MARSHALL WARD, and has been continued at Pretoria, at the Transvaal Department of Agriculture, where the author is mycologist. This first paper deals with the development of the uredo-mycelia, and the principal results are as follows: In the early stages of the mycelia, these species exhibit distinctive morphological characters; the sub-stomatal vesicle is of a definite shape for each species; the haustoria of some species are very distinctive; and in some species a well-developed appressorium is present, while in others it is not so evident.-J. M. C.