226 BOTANICAL GAZETTE [September 



color developed, which gradually changed to a reddish brown 

 precipitate. The normal color change is a green solution at first, 

 changing to a black precipitate. It is possible that the fungus 

 yielded during the acid distillation some substance other than 

 furfural which reacted with the phloroglucin. Furthermore, the 

 media in this case contained no pentose substances whatever; 

 hence it is very unlikely that the fungous bodies would produce 

 more furfural-yielding materials here than in the other cases, where 

 the possibilities of enmeshed pectin were present. The high value 

 for no. 572 is explainable by the fact that the felt grew on a firm gel 

 of calcium pectinate, making it difficult to obtain a clean separa- 

 tion of mycelium from medium in preparing the samples for 

 analysis. 



From these data it is evident that only a very small amount 

 of pentosan is present in the felt of Sclerotinia cinerea, either as 

 enmeshed pectin or as a constitutional substance. Whether the 

 latter actually exists is not proved by the data. Furthermore, 



microchemical tests failed to show pectic substances in any portion 

 of the hyphae. 



A possible function of the enzyme pectase in a fluid medium, 

 such as fruit juice, is suggested when the characteristics of the 

 growth of Sclerotinia on such a medium are taken into consideration. 

 These juices always contain soluble pectin; they also contain some 

 calcium, but there is never any formation of calcium pectate with- 

 out the presence of the fungous hyphae. As soon as the germinating 

 spores in these media have begun to form a slight weft, this weft 

 can be lifted from the medium with a mass of gelatinous material 

 clinging to it. In fact, the young felt consists of a relatively small 

 mass of hyphae imbedded in a large mass of the gelatinous coagu- 

 lum. This coagulum can be removed by gentle pressure through 

 cheesecloth in the case of young felts. As they grow older, how- 

 ever, the hyphae increase in bulk, become closely packed together, 

 and the coagulum loses water and becomes firm and slippery. A 

 mature sporulating felt consists typically of ftree layers: an 

 upper white layer of loosely packed hyphae bearing the sporo- 

 phores; a middle layer of black, leathery, closely packed mycelium; 

 and a lower layer consisting of a few hyphae and the concentrated 



