212 



KNOWLEDGE, 



[NovriMHKii 2, 183G. 



apoplectic hippopotamus, and like it occupies (in more 

 senses than one) a very high place. Both animals are, in 

 fact, the only representatives alive of distinct families ; the 

 hippopotamus leans towards the pig, the giraffe is a deer 

 with a dash of antelope. In its general structure it is not 

 markedly different from either. Its horns are most in- 

 terestingly intermediate. They are but small, considered as 

 functional horns ; but the smallness in size is made up by 

 numbers, for the giralTe has throe horns, one in the 

 mi<ldlo and one on each side. The latter are bony pro- 

 jections covered with a persistent skin. In being bony pro- 

 jections they are like the horns both of deer and antelopes. 

 In being covered with hairy skin they are like deer, whose 

 "velvet" everyone knows; but in the fixedness of this 

 velvet, which is not shod, the giraffe is an antelope. 



PARASITIC LEAF-FUNGI. 



By Rev. Alex. S. Wilson, M.A., B.Sc. 



ABOUT the time when the blackberries are ripe, 

 after a short search one can generally find a bush 

 the leaves of which have a paler appearance than 

 ordinary ; closer inspection shows the under sur- 

 faces of the leaves flecked here and there as if 

 with specks of soot. With the aid of a pocket lens each 

 speck is seen to consist of tufts of little club-shaped bodies, 

 and if we scrape some off', mount them on a slide, and 

 place it under the microscope, we see that they are 

 cylindrical cells, each made up of from three to eight joints, 

 and supported by a short stalk. Their form is so 

 characteristic that, once seen, there is no difficulty in 

 recognizing it again. These are the telutospores of the 

 bramble brand {Pliraiimidium violaceum), a parasitic fungus 

 belonging to the order J-'ridioiiu/ci'tes (or I'l-i'dini's), aM of 

 which inhabit living plants. 



The leaves of various species of mint are in autumn 

 often dotted over in like manner with dark-coloured 

 spots, due in this case to the telutospores of Pwrinia 

 mentlta, each composed of two joints of hemispherical 

 form. By this two-celled character the Puccinia genus is 

 distinguished from Phragmidium, which has telutospores 

 usually consisting of more than three joints. On the 



meadow- sweet a brand, Tii- 

 pliniijmidiiim ulintiii(e,occu.rs, 

 having three-celled teluto- 

 spores ; those of the brands 

 which affect the bean, pea, 

 clover, and lady's-mantle, 

 species of Uromyces, are uni- 

 cellular. Gijmnosjioriinghim 

 (7i()sf('/(V()growin,t; on junipers 

 has them two-celled, closely 

 packed, and embedded in 

 gelatinous substance ; they 

 are prismatic, and form a 

 Fig. 1.— Telutospores. \._Phran. compactlayer in Melamspora 



infesting the leaves of the 

 willow and sunspurge ; and 

 the species of Colesporium 

 living on the colt's-foot and eye-bright have four-celled 

 telutospores united to form a compact, waxy stratum, 

 surroimded by a gelatinous mass. The characters pre- 

 sented by their telutospores thus form the basis of the 

 classification usually followed in this group of fungi, the 

 spores of which, indeed, constitute the principal feature. 



Telutospores are resting or winter spores ; only in a few 

 cases are they capable of immediate germination. The 



midium violaceum. 2. Puccini, 

 menfhte. 3. P. riolariim. I, 

 P. graminia. 



name, derived from /I'^o.v, "end," indicates that their produc- 

 tion is regarded as completing the life cycle of the fan^nis. 

 Unlike other spores, which on germination give rise to a 

 branching mass of thread-like cells known as a mycelium, 

 which is really the vegetative body of the fungus, a teluto- 

 spore only dovolopa a short filament or promycelium, on 

 which arise small reproductive cells, the sporidia ; the 

 latter are able at once to germinate and form mycelia. 



?ilinute yellow streaks may be observed during the latter 

 half of the year on the leaves of all our common grasses, 

 especially on the lower leaves, by anyone who will take 

 the trouble to look for them. On examining these with 

 the pocket lens they are found to be chinks in the 

 epidermis of the leaf filled with orange-coloured dust. 

 Under a microscope of low power, with direct light, a small 

 piece of grass-blade so affected presents a charming 

 appearance. The dust is seen to be composed of orange- 

 red globules, having a waxy lustre or bloom, reminding 

 one of artificial fruits, and forming a splendid contrast to 

 the bright-green chlorophyll grains of the leaf. With 

 careful focussing under a higher power, minute projections 

 studding the surface of the spores become visible, giving 

 them a bristly appearance. These are the summer or 

 uredospores of a parasitic fungus now designated Puccinia 

 ruhir/o rem, one of the corn-rusts which occasionally 

 inflict so much damage on cereal crop 3. Pnccinin iji-aminis 



injures the wheat ; allied 

 species occasion the orange and 

 scarlet patches of rust seen on 

 the rose, barren strawberry, 

 eye-bright cow-wheat, sow- 

 thistle, groundsel, thistle, 

 harebell, nightshade, dog's- 

 mercury, and many other 

 native plants. The name 

 uredospore {uru, " I burn ") 

 has reference to the con- 

 spicuous disfigurement and 

 often burnt appearanceof leaves 

 attacked by these faugi. Un- 

 like telutospores, the uredo- 

 spore germinates at once if 

 placed on a suitable host, 

 and gives rise to a filament 

 which penetrates the epidermis and develops into a my- 

 celium, extending through the intercellular passages of the 

 leaf. Uredospores commonly appear somewhat earlier in 

 the season than telutospores, though the two often grow 

 together. 



On gooseberries our readers may sometimes have re- 

 marked a bright yellow spot about the size of a sixpence. 

 Similar spots occur on the leaves of gooseberry and currant 

 bushes. The lens shows that they consist of a number of 

 small round openings full of orange powder ; these are the 

 cluster-cups and meidiospores of .F.cidium i/rossularia. An 

 exceedingly common species, .!•,. compositarum, is found on 

 the lower surface of the colt's-foot leaf, a plant abundant 

 on every railway embankment. Plants may possess more 

 than one species of parasite ; on the colt's-foot there also 

 occurs a species of Colesporium, and nearly a score of 

 different fungi are stated to take up their quarters on the 

 leaves of the nettle. Each species of a^sidium confines 

 itself, as a rule, however, to plants of a particular family, 

 or even selects its hosts from a single species ; thus the 

 necidia of the berberry, hawthorn, honeysuckle, Scotch fir, 

 mountain ash, anemone, buttercup, nettle, primrose, violet, 

 willow-herb, bedstraw, dock, and many other plants are all 

 diff'erent and belong to distinct species. Seen with the 

 lens the cluster-cups present the appearance of a group of 



Fio. 2. — tiermiuatiiig Teluto- 

 spores, with promvcelia and 

 sporidia (sp.). 1- P/irngmi- 

 diiim. 2. Triphratimidium. 



