244 PROCEEDINGS OF THE AMERICAN' ACADEMY. 



is evident from the sprouting out of several small hyphae, not only 

 from the end hut also from the sides near the end of the injured part ; 

 and these often twine about each other in such numbers, that it gives 

 the appearance of a broom-like structure. 



The bulbils. — Often within forty-eight hours, dark bodies, which 

 eventually become black, may be observed with a hand lens, scat- 

 tered over the substratum or in it; they are most abundant near the 

 point of inoculation, from this point extending out as the peripheral 

 growth of the mycelium increases thus exhibiting a progressive forma- 

 tion. These black bodies are bulbils which soon become very numer- 

 ous, forming a blackish crust over the substratum and usually giving 

 the whole culture a black aspect. This is especially true when it is 

 grown on such media as potato agar made very hard with about forty 

 grams of agar to the litre. In such cases the mycelium is quite scanty 

 and procumbent, and the bulbils thus become very conspicuous; 

 while on media like rat dung, where there is an abundance of myceli- 

 um produced, they are not so readily seen, since they are usually 

 formed on or in the substratum. In the development of these struc- 

 tures which are produced so abundantly, two or three intercalary 

 cells become enlarged and filled with granular nutrient material, as 

 shown in Figures 11-14, Plate 1. From these cells others are produced 

 by budding, or short branches are formed which surround the prim- 

 ordial cells, and which in turn become enlarged so that eventually 

 there is produced an almost spherical bulbil somewhat flattened, 

 75-100 £i in diameter, the cells in the center, usually considerably 

 larger, but all filled with protoplasm, without any definite differentia- 

 tion of cell-contents between internal and external cells. Not infre- 

 quently, however, the marginal cells of old bulbils lose their contents, 

 although they retain the dark color in the wall, but this is probably 

 due to age. As a result of the unequal production of marginal cells, 

 the bulbils may vary considerably in size and some become quite 

 irregular in outline. Frequently the bulbils or the primordia of im- 

 perfect ones, especially as the cultures become old, heap together and 

 form conspicuous dark elevations scattered over the substratum. 

 These structures eventually assume a yellowish color, probably due 

 partly to fading and partly to the immature bulbils that compose 

 them. 



The apothi riiini. — Occasionally there is found a spiral primordium, 

 as shown in Figure 1, Plate 1, produced on short lateral branches 

 which usually divide diehotomously, sometimes of the second or third 

 order, the ultimate branches of which coil up spirally (Figures 1-4, 



