ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 97 



Rhizomorpha subcorticalis of Armillaria mellea.*— M. J. de Seynes 

 states that, iu the initial stage of its development, the Bhizomorpha sub- 

 corticalis appears as a white fibrous membrane more or less flabelliform, 

 and agrees with Leveille's definition of the hymenoid mycelium of 

 Armillaria mellea. The author further states that he has observed in 

 certain cases a tendency of the extremity of the rhizomorph to divide 

 into lobes, and these are easily detached from the wood on which the 

 fungus is growing. 



In conclusion, the subject of these observations is described as a 

 mixed organ representing not only a condensed membranous mycelium, 

 but sterile, deformed, and flattened receptacles. A few lines are also 

 added on its mode of phosphorescence, which is stated to be exclusively 

 nocturnal. 



Uredineae.t — Herr P. Dietel enters into several points of comparative 

 anatomy in the Uredineae. One of the more important features of varia- 

 tion within the family is in the teleutospores, while very little variety is 

 exhibited by the uredospores or aecidiospores. The secidia of Gymno- 

 sporangium differ from those of the other genera in not being saucer- or 

 cup-shaped, but comparatively long flask-shaped structures. 



The greatest point of variability in the teleutospores is their size, 

 and the number of cells of which they are composed, this varying even 

 within the same genus. In addition to the normal bicellular teleutospores, 

 unicellular spores often occur, which have been termed " mesospores," 

 from an idea that they are intermediate structures between teleutospores 

 and uredospores. Tulasne, on the other hand, regards them as having 

 arisen by the abortion of the lower cell of the teleutospore, thus exhibiting 

 the affinity of Puccinia with Uromyces, the latter being degraded repre- 

 sentatives of the former. Herr Dietel, while agreeing with this view 

 on the whole, thinks it more probable that Puccinia has sprung from 

 Uromyces by progressive development. 



The teleutospores also vary greatly in their form ; and this is some- 

 times the case even in the same species, especially where it occurs on 

 several different hosts. The occurrence, in certain species of Puccinia, 

 of teleutospores consisting of three or more cells has been thought to 

 indicate a transition to the genera Phragmidium and Tripliragmium ; 

 but the author considers that this is rendered improbable by the very 

 different phenomena of germination exhibited by the spores of these two 

 genera. In Puccinia germination takes place by a single pore at the 

 upper end of each cell ; in Phragmidium by several pores in the equa- 

 torial zone of each cell. The nature of the surface of the outer mem- 

 brane of the teleutospore is also variable, especially in Uromyces and 

 Puccinia ; the two constituent spores may differ from one another in this 

 respect, or may be alike. Great difference is also exhibited in the colour 

 of the spores. 



The Uredinefe are generally regarded as most nearly allied to the 

 Ascomycetes; but the homology of the different kinds of spore is 

 attended with difficulties. Schroter regarded the teleutospores as homo- 

 logous to the asci. The frequent appearance of spermogonia without 

 secidia before the uredo-generation can only be explained by the abortion 



* Bull. Soc. Bot. France, xxxiv. (1887) pp. 286-7. 



t Bot. Centralbl., xxxii. (1887) pp. 54-6, 84-91, 118-21, 152-6, 182-6, 217-20. 

 246-50 (1 pi.). 



1888. h 



