. The British rust fungi (Uredinales), their biology and classification. Uredineae. 78 PHYLOGENY are always, or usually, so placed. For instance, in Melam- psoridium betulinum the teleuto-sori almost invariably originate directly below the stomatal pore. The cause of this cannot be merely the need of oxygen for respiration, since it has been shown that the intercellular spaces of a leaf are all well supplied in that respect. Fig. 37 is drawn from the lower epidermis of a leaf of Betula alba in which teleuto-sori were just beginning to be produced. The same thing is true of the teleuto-sori of
. The British rust fungi (Uredinales), their biology and classification. Uredineae. 78 PHYLOGENY are always, or usually, so placed. For instance, in Melam- psoridium betulinum the teleuto-sori almost invariably originate directly below the stomatal pore. The cause of this cannot be merely the need of oxygen for respiration, since it has been shown that the intercellular spaces of a leaf are all well supplied in that respect. Fig. 37 is drawn from the lower epidermis of a leaf of Betula alba in which teleuto-sori were just beginning to be produced. The same thing is true of the teleuto-sori of Melanipsora Larici-epitea and other Melampsorae,Sind apparently even of Phragmidium. In others of the lower groups, Uredin- opsis, Milesina, etc., uredo-sori are equally so placed, both. Fig. 37. Melampsoridiian betulimnn. a, young sori of teleutospores, viewed through the epidermis, showing how they originate beneath a stoma; at the lower right-hand is a sorus with only two teleuto- spores, X 300; b, three young teleutospores, forming a similar sorus, seated on a common base, x 600. primary uredo-sori (which represent secidia) and secondary. It can be justifiably inferred that this was the primitive position in which the female gametes and afterwards the other kinds of spore-sori were formed at the beginning: in Puccinia and its allies this position is no longer maintained. Since in the Ustilaginales (a comparatively non-progressive, if not degraded, group) there is only one kind of spore besides the basidiospore and the ensuing conidia, and this is produced irregularly and not in definite sori, it may be inferred that the same was true of the primitive Uredinales. This one kind of spore must have been the equivalent of the teleutospore. It is. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Grove, William
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