1889.] MICROSCOPICAL JOURNAL. 3 



which, when older, will become broken up by partitions. It is well 

 to draw one or more of the hyphae with all the branches. While doing 

 this it may be necessary to move the slide about. If so, care should be 

 taken not to draw different parts of the hyphae on different scales. A 

 camera lucida will help in drawing. 



Having noted carefully and drawn the outline of one hypha of the 

 mycelium, next, with the highest magnifying powers and best illumi- 

 nation, examine in greater detail some single portion of one of these 

 hvphae. Its interior will show patches of lighter and darker color. 

 Very skilful staining would help in demonstrating these, but it is rather 

 difficult. To stain, irrigate with haematoxylin, which, when afterward 

 cleared with alcohol, will make the light and dark patches more conspic- 

 uous. Careful study of the lighter patches will show that they are vacant 

 spaces in the centre of the hypha surrounded by a darker exterior 

 substance. The former are vacuoles ; the latter, the protoplasm, of the 

 hypha. Along the tube in the protoplasm may be seen dai"k spots, 

 the nuclei of the protoplasm. The hypha is not green colored, and 

 contains no trace of green bodies such as are found in protococcus. 

 The mycelial hyphae being left for a day or two in pure water the con- 

 tents of the hyphae will disappear, and the clear, empty hyphae will be 

 seen like the dead cell-walls of yeast. They have no power to retain 

 life except they be fed. See figure 2. 



^. The Aerial Hyphae. — These are derived by branching from the 

 mycelial hyphae. They are short and cut across by transverse parti- 

 tions, as are some of the mycelial hyphae near where they arise. These 

 hyphae are peculiar because of the very complicated growth to be found 

 at their tips. The plan of arrangement at the tips of the erect hyphae 

 is not easy to discover. It is helpful to mount the specimen in dilute 

 caustic potash (5%)i but it can be made out in an alcoholic mount. It 

 will be seen that the small spheres or conidia are arranged in rows like 

 a string of beads, and at the base of each row a single large piece can 

 be seen (fig. 4). This is the basidium. One of these basidia is at 

 the base of each row of conidia. Several basidia are carried in turn by 

 one joint and a similar joint bearing a similar lot of basidia and conidia, 

 or perhaps several others may be borne upon the end of one erect 

 hypha. All these parts form a sort of broom-shaped expansion on the 

 hypha, far more complicated in fact than is shown in the figure. Closer 

 examination of the basidium will show that it is pointed above ; that 

 the conidium grows from this cone, and that the other conidia are held to- 

 gether by a fine connective piece not shown in the figure. When these 

 observations have all been made and recorded by sketches, the chief 

 facts in the structure of the mould will have been made out. 



6. Physiology. — The uses of the various parts of this organism 

 may be noted briefly. The mycelium, spread out over the surface of 

 the nutrient host, absorbs from it the substances which as food promote 

 the growth of the parasite. The aerial hyphae, on the other hand, have 

 nothing to do with absorption of food from the host, and are wholly 

 concerned in producing certain buds — the conidia — which are especially 

 well adapted to a wide distribution from their minute size. The conidia 

 themselves are spores from which may grow an entire new mycelium. 

 Any hypha could grow and produce a mycelium, but the conidia are 

 far more favorable both for preservation and distribution than ordinary 



