264 DIVISION II. —COURSE OF DEVELOPMENT OF FUNGI. 



small brush-like bodies is a separate plant. The entire length in the largest known 

 species, Laboulbenia Nebriae, is about 1 mm., in most species little or not more 

 than o'5 mm. The phenomena observed in them most nearly resemble those known 

 in the Ascomycetcs, and arc named accordingly. The small plant (Fig. 120) is 

 attached to the substratum by a filiform or clubshaped stalk, consisting usually of 

 two cells one above the other; at the apex of the stalk is a perithecium and a body 

 which may be here briefly termed an appendage (a). The perithecium is narrowly 

 conical in form or flask-shaped and in some species oblique, and consists when 

 mature of a wall formed of a few cells disposed in two layers at the base and one 

 layer at the sides with a narrow orifice at the apex ; the group of asci which rises 

 erect from the base of the perithecium is closely surrounded by its wall. The number 

 of the asci and the way in which the spores are formed in them are not exactly 

 ascertained. The number of spores in an ascus is said to be 8 and 1 2 ; the ripe 

 spores are fusiform and colourless, and being divided by a transverse wall into two 

 equal cells are therefore compound and bicellular ; they escape singly and one after 

 another through the orifice of the perithecium, no doubt in consequence of the 

 gelatinous deliquescence of the wall of the ascus. The appendage springs from close 

 to the base of the perithecium in the form of a segmented hair or filament, varying, 

 according to the species, in length and number of cells and presence or absence of 

 branches, which in some species are very peculiar in their form and arrangement. 

 All the cells in the mature Fungus except the asci, the spores, and the extremities of 

 the branches of the appendage, have very thick membranes of a deep and often a dark 

 brown colour. 



The Laboulbenieae have no mycelium ; the ripe double spore attaches itself by 

 one extremity to the chitinous covering of the insect, and sends into it a small short 

 point, which sometimes enlarges into a knob at its extremity and with the surrounding 

 chitin soon assumes a brown colour ; this point is its only organ of attachment and 

 of nutrition. Thus firmly planted it developes at right angles to the substratum and 

 reaches its mature state by the necessary successive cell-divisions and differentiations. 

 Most of the details of these formations can be seen at once in the accompanying figure 

 for the case which it represents, but some important points have still to be cleared up. 



I select the following for special notice, and refer the reader to Peyritsch's treatises for 

 further details. The appendage is developed from the cell of the double spore which 

 is the upper one in reference to the point of attachment ; it is therefore originally 

 terminal and is completed before the perithecium. The stalk and the perithecium 

 are formed from the lower cell of the double spore; the perithecium shoots out laterally 

 from beneath the point which is afterwards that of insertion of the appendage, and 

 as it increases in breadth it thrusts the appendage to one side. In its earliest stage it is 

 unicellular; as it grows it divides by successive transverse divisions into three tiers of one 

 cell each, and each tier in acropetal succession then separates by longitudinal division 

 into an axile and several parietal cells. But before the longitudinal division begins 



I I .aboulbenia vulgaris), or before it has reached the uppermost tier-cell (Stigmatomyces), 

 it is observed that this cell puts out a short protuberance at its apex, which is either very 

 thin-walled or seems to have no membrane, and disappears again at a later stage of the 

 development (Fig. 120,;', //). Simultaneously with the formation of this protuberance on 

 the primordium of the perithecium small thin-walled swellings arc seen on the apex or 



