334 Agricultural Experiment Station, Ithaca, N. Y. 



centric lines which are quite pronounced on the colony. At the 

 center of the colony there is developed quite a compact stroma which 

 is very much like that on a more solid substratum, like the stems of 

 the vetch or bean. This stroma may be quite extensive and irregu- 

 lar in outline witli a few outlying smaller and scattered ones, or 

 there may be quite a large number of them at the center of the 

 colony, the larger ones of course nearer the center and the smaller 

 ones at the periphery. These individual stromata are so far like 

 those developed in solid substrata, either in nature or culture tubes, 

 that they are margined with the characteristic satae. A photograph 

 of several of these growing in the agar in a Petrie dish is shown in 

 Fig. 52, plate YI, left upper corner. The photograph was taken 

 from directly above and is magnified about 60 diameters. 



In a few days after the appearance of the colonies the basidia 

 begin to develop. Some of them and probably the first ones are 

 prostrate and wholly or partly immersed in the agar. They may 

 be simple, or branched, when the branches may be opposite, or 

 irregular, and in some cases the branches are assurgent, when most 

 of them are thrown to one side. There is a strong tendency for 

 the threads of the mycelium to assume a moniliform appearance by 

 the swelling of the short cells thus producing a strong constriction 

 at the septa. This tendency to a swelling of the cells of the 

 mycelium is also shown to some extent in the basidia. Quite early 

 many of the fruiting threads become erect and branch several times,^ 

 the ultimate branches forming the basidia. The branches and the 

 basidia are frequently opposite or whorled and when standing alone 

 simulate very well the conidia fructification of a Yei'ticilUum. For 

 some time the conidia are held in chains as they are developed suc- 

 cessively on the same basidium. When moisture is suflicient, and 

 this is usually the case in the Petrie dish, the capillarity of the film 

 surrounding the conidia pulls them from the concatenate posi- 

 tion and they are gathered into a globular head appearing as if they 

 were developed in the form of a Mucor. Very soon at the center 

 of the colony by the development of numerous fertile hyphae 

 very closely, a true stroma is formed, and the conidia are held by 

 capilliarity in great masses upon the summit of the stroma. 



After 24th a cell culture was prepared in a droj) of nutrient agar 

 at 5 p. m. On the following day the conidia were germinating and 

 a group of them was photographed (46, Plate Y, upper left corner). 

 The spores here at this time were 4-5^ in diameter. The germ 



