NATURE OF THE SPERMATIA circumstances, would shew quick and luxuriant growth : tln-v cannot be degenerate conidia, because the nucleus is large and well-formed though at times no nucleolus can be seen.(5) Poaeon Poa. Race 1 grows not only on Rye, but also on Hordeum vulgare, H. murinum, Agropyron repens, A. caninum, Elymus arenarius, Bromus secalinus etc. (In all these enumerations non-British species will be omitted.) Race 2, on Oat, and on Arrhenatherum elatius, Dactylis glomerata, Alopecurus pratensis, Milium effusum, Bromus arvensis, B. madritensis, Festuca Myurus, F. sciuroides, F. ovina (tenuifolia). Race 3, on Wheat, but also though more rarely on Barley, Oat, and Rye. Race 4, on Aira caespitosa. Race 5, on Agrostis canina, A. stolonifera, A. vulgaris. Race 6, on Poa compressa, P. caesia, P. pratensis. A seventh Race, f. Hordei, is sometimes added, though Eriksson included it under his f. Tritiei or f. Secalis. Jaczewski (1910) from numerous inoculation-experiments arrived at somewhat different results : he found that he could infect Rye only from Agropyron repens, A. caninum, Bromus secalinus, and Dactylis glomerata; Wheat only from A. repens, Festuca gigantea, and Lolium perenne ; Oat only from G. u.

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Pleodorina Illinoiensis. swims freely about, even after the sporangium has grown nearly as large as itself. To see the two in that condition, twisting, turning, doubling, backing, rolling over one another, reminds one of the gambols of two dogs fighting in a half-friendly way in a field, or of two equally matched boys wrestling upon a lawn. The Chlamydomonas, judging by its antics, is evidently excited and uncomfortable under the infliction, but at length it succumbs and becomes motionless: its protoplasm disintegrates and discolours, the sporange reaches its full size, the beak develops and tbe zoospores begin to escape through the mucus. When all are gone, the mucus has disappeared; the opening, which is often wider than a zoospore, is clearly seen, its edges curling back and giving the empty sporange an urn-like shape. The complete evacuation may occupy a period of more than an hour or two. During all the time of observation no resting spores were seen, nothing but zoosporangia, and all these were of exactly the the same character. Dangeard (" Le Botaniste," i., 61, pi. 3, Fig. 12-15) reported i?. g' ZoftosziWi as occurring on Chlamydomonas; the account given agrees in its details with those of R. actifovDie as here described, except that the sporangia are said to allow the zoospores to escape through fotir or five little boles, which would thus bring the parsisite under R. globostim. Nothing approaching this was seen in the present instance; in every one of the hundreds of cases observed the single opening was always exactly apical.

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