1865.] Microscopic Fungi. 35 1 



ber of the species thus added depend for their specific as well as their 

 generic characters, upon microscopical examination. At the present 

 day the British species of flowering plants scarcely exceeds three- 

 fourths of the number of Fungi alone. 



Mr. Cooke desires to turn the attention of lovers of science to 

 these minute objects, and to induce them to apply their microscopes 

 in tracing out their structure and mode of reproduction. He illus- 

 trates the organic forms and structure of numerous kinds of moulds, 

 aud gives coloiu'ed representations of them. He refers to the cluster- 

 cups, spores, spermagones, steriginata, stylospores, and other structures 

 in Fungi, but he fails, we think, in making them intelligible to a mere 

 beginner. The work seems to be rather fitted for one who has ac- 

 quired preliminary information on the subject. There is a vast accu- 

 mulation of interesting facts (not, however, always noticed in simple 

 and clear language), and much that is fitted to arouse attention to the 

 subject in hand. 



Speaking of the iEcidiuni of the Goatsbeard, the author remarks : — 

 " If we compute 2,000 cluster-cups as occurring on each leaf, and 

 suppose each cup to contain 250,000 spores, we shall then have no 

 less than five hundred millions of reproductive bodies on one leaf of 

 the Goatsbeard (Tragopogon), to furnish a crop of parasites for the 

 plants of the succeeding year." This gives some idea of the enormous 

 production of germs in these plants. No wonder that they are dif- 

 fused through the whole atmosphere, ready to fix their abode on any 

 substance where they can find pabulum. The production of mould 

 everywhere depends on the existence of these unseen microscopic 

 germs in the air around us. 



Fungi exhibit remarkable changes of form according to the 

 element in which they grow. Hence the diversified forms assumed by 

 Penicillium glaucum, and other kinds of mould when found growing 

 at one time on trees, at another on animal tissues, and at another time 

 on syrup. In speaking of Dimorphism in Fungi, Mr. Cooke points 

 out that the same fungus often passes through two marked conditions 

 — one being the imperfect and undeveloped, the other the fully 

 developed state. " One plant, for instance, sprinkled over the under 

 surface of a rose-leaf, like turmeric powder, has its mycelium or 

 root-like threads (spawn) penetrating the tissue, whilst bearing above 

 its spherical golden-coloured spores. Its vegetative system is com- 

 plete, and apparently its reproductive also. Hence it seems to claim 

 recognition as a perfect plant, and under the name of Uredo Bosce, 

 was so recognized, until microscopical investigation determined other- 

 wise. Thus it has been discovered that certain dark-brown spots, 

 which appear later in the season, are produced upon the same 

 mycelium, and are indeed aggregations of more perfect and complex 

 fruits of the same plant. Before this point was satisfactorily decided, 

 the brown spores, which are borne on long stalks, and are themselves 

 septate or divided by transverse partitions into a complex fruit, 

 received the name of Puceinia Bosce." Thus, two plants, which he 

 thus referred to different genera, were found to be one and the same 

 species in different conditions. 



