274 PROCEEDINGS OF THE AMERICAN ACADEMY. 



On horse and dog dung from Cambridge, ^Massachusetts, and rabbit 

 dung from Innerkip, Ontario. 



Both the bulbils and the mycelium usually' grow more or less below 

 the surface of the substratum. The former are often found immersed 

 more than a centimeter. It is easily distinguished from P. polyspora 

 by its mode of development and from P. pannosa by its color, the 

 latter being black. It resembles most nearly 7-". irregularis, from 

 which it may be distinguished by its darker color, the size and con- 

 spicuous contents of the cells of the bulbils and the fact that the 

 latter become more or less imbedded in the substratum. 



The mycelium, since it is formed largely in the substratum, is in- 

 conspicuous in tube-cultures and is composed of large swollen hyaline 

 cells, densely filled with oil globules and often much contorted 

 (Figure 17, Plate 10). In older cultures the cells lose their contents. 



This fungus was grown on different kinds of media, but could not 

 be induced to develop any other mode of reproduction. It grows 

 well on bran and horse dung agar, the bulbils often becoming very 

 large and numerous just below the surface of the substratum, forming 

 almost a continuous layer, and often producing a more or less hard 

 crust. In contrasts of mycelia in plate cultures, a marked heaping of 

 the hyphae occurs where the two mycelia come together, and the 

 bulbils seem to be somewhat larger, and more irregular in this region, 

 but no other marked difference was observed. 



The bulbils. — The primordium of the bulbil consists of one or more 

 intercalary cells which become much enlarged. For example, Figure 

 17, Plate 10, a later stage of which is seen in Figure 23, shows several 

 such cells, all of which would have taken part in the formation of a 

 somewhat elongated irregular bulbil, such as is shown in Figure 23. 

 On the other hand. Figure 18 represents a primordium which consists 

 of a single cell, and Figures 19-22 are further stages in its de\'elop- 

 ment. In the latter case a more or less spherical bulbil is the result 

 (110-148 yu in diameter), while in the former it is more irregular, 

 often exceeding 2(j0 fx through the long axis. The method of enlarge- 

 ment, however, is exactly alike in both cases, that is, short lateral 

 branches are produced from the bases of which are cut off a series 

 of short cells which enlarge, becoming spherical at first and later, as 

 the bulbil increases in size and the cells are subjected to lateral pres- 

 sure, forming a compact angular mass in the center. Occasionally 

 the branches are replaced by cells which, arising as lateral buds, 

 become spherical and in turn give rise to other buds, the lateral 

 walls of which adhere closeh' and ultimateh' form a more or less 



