370 



MONOGRAPH OF THE LABOULBENIACE^E. 



in the group, while the origin of its perithecia is quite unique. Starting with the slender spore, 

 the basal segment of which is far shorter than the terminal, the young plant begins its develop- 

 ment by the formation of numerous transverse partitions in both segments (tig. 1). The distal 

 cells give off a variable number of simple branches, and in the mean time longitudinal divisions 

 appear here and there (fig. 2), which become rapidly more numerous (fig. 3) until the main 

 body is for the most part divided into small, very numerous, squarish cells (fig. 4). The main 

 body of the fungus then assumes a more or less clavate form, and is terminated by what may 

 be called the primary appendage, the basal cells of which may have a few longitudinal septa 

 (fig. 5), the distal ones producing long, slender branches. A more rapid growth peripherally 

 of the portion below the base of this primary appendage causes the wall-cells in this region to 

 arch outward, producing a more or less distinct cavity, completely enclosed within, as is indi- 

 cated in fig. 5. As this cavity enlarges, secondary appendages begin to grow inward and upward 

 from the inner surfaces of the cells formiug its lateral walls ; while from the cells forming its 

 floor the perithecia arise. As a result the secondary appendages break through at the base of 

 the primary appendage, which is turned to one side and soon disappears. This condition is 

 shown in fig. 6, in which the terminal cavity is indicated partly as if seen in section, the second- 

 ary appendages having burst out above it and turned the primary appendage to one side, its 

 base being represented at the left. The cavity goes on enlarging till the perithecia begin to be 

 protruded within the circle of secondary appendages (fig. 7) ; while by further general growth 

 the mature condition is finally reached, as represented in fig. 8. A longitudinal section through 

 the fertile portion of an adult individual then presents the condition shown in fig. 9, which is 

 drawn from a microtome section kindly made for me by Dr. Richards, but is to some extent 

 diagrammatic. Half only of the cup-like extremity is represented, the rim at the right showing 

 the sterile secondary appendages arising from its inner face. The flattened bottom of the cup 

 is seen to consist of crowded parenchyma cells, from which arise directly the perithecia in vari- 

 ous stages of development, and the small and inconspicuous antheridial appendages. The latter 

 consist of a few, usually three, superposed, rather short cells, bearing at the tips (figs. 21-23) 

 one to three (usually two) rather large, rod-like bodies, which must be considered exogenous 

 antherozoids, and suggest in a way the spermatia of some lichens. These appear to be formed 

 successively, as in the case of Ceratomyces ; but owing to the comparatively small size of the 

 antheridia and the difficulty of observing them in crushed specimens, this point could not be 

 definitely ascertained. The antherozoids themselves evidently fall off ; since they may fre- 

 quently be found lying loose about the bases of the perithecial stalks, and in this position they 

 seem to be sought out by the trichogynes, which at first invariably grow downward (figs. 9 

 and 16). 



The development of the perithecium is illustrated by figs. 10 to 20 and fig. 25. They arise 

 primarily as an outgrowth or upgrowth from one of the superficial cells forming the bottom of 

 the cup. This protrusion elongates and becomes divided by two septa into three superposed 

 cells (fig. 13). Of these cells the upper, as far as can be determined, follows a development simi- 

 lar to that by which the perithecium is usually formed in members of the group dividing into 

 two primordial cells (fig. 14), the lower of which forms the perithecium proper, the latter the 

 procarpe. The trichogyne is always simple and terminal, consisting of a filament of variable 

 length, which, as has just been mentioned, grows downward (fig. 16) towards the base of the 



