HALF-AN-HOUR AT THE MICROSCOPE. 115 



tremely slender and transparent, the latter short, closely borne, 

 and either alternate or opposite. I should have liked to have seen 

 fruit on the specimen. The interest of this slide is increased 

 through its having also some good illustrations of such Diatoma- 

 ceae as grow along with it, in small boggy streams. Amongst 

 them may be noted Himantidium pectinali, AfelosU'ci variaiis^ 

 Meridion circiilare^ and Syncdra radians. I suppose the specimen 

 to be mounted in one of the camphor solutions, which really 

 seems to me to be disposed rather than otherwise to favour the 

 growth of that tiresome fungous mycelium, which is such a plague 

 to some of our best slides. I should be disposed to try if a weak, 

 spirituous solution of corrosive sublimate could not be introduced 

 at one edge of the covering glass^ so as to stop the inroads of the 

 pest, and so save a valuable mounting. 



Aregma bulbosum (PL XIII., Figs, i — 8). — This fungus (in a 

 way not yet sufficiently understood) gains access to the interior of 

 the plant appointed for its "host." At the seat of development (the 

 leaves) a cushion of mycelial filaments is formed; numerous 

 branches appear, the tips of which swell, become constricted, and 

 the separated portions are cast off as " protospores," capable of an 

 independent vegetative existence. These protospores have their 

 analogues in the " bulbilli " of mosses, jungermaniae, ferns, and 

 the " gonidia " of lichens, as also in the " bulbs " of the tiger-lily, 

 and a few other of the higher plants. They differ from true 

 " spores " and seeds in not being products of generation, but 

 simply portions of tissue specialised to a sufficient degree to be 

 capable of independent life. By rapid internal growth of the 

 fungus, the epidermis of the leaf is raised in blisters, and bursts. 

 The earlier condition adverted to receives in the bramble the 

 name of Lecythea rubornm. After this, more branches, swollen at 

 their tips, are formed. The contents become increasedly granular, 

 and mapped out more and more distinctly into four portions, the 

 " endochromes," in each of which appears a clear vacuole, the 

 " nucleus." The subsequent changes consist in increased differen- 

 tiation of structure, the formation of a horny, brown outer coat 

 around the cell-contents, but within the original cell- wall — i.e.^ the 

 branch. The distinct appearance of "pearly beads" form corru- 

 gations on the outer cell-wall. It is hoped that by the aid of the 

 figures on Plate XIIL, these various processes will be understood. 



The plan of duplex mounting adopted by some of our mem- 

 bers is worthy of high commendation. In the Plate, figures of 

 related forms have been added, to tempt members whose attention 

 has not yet been turned to these beautiful and interesting objects 

 to collect and study them. 



