FUNGI. 71 



There are numerous common species of Eurotium, differing 

 in color and size, some being yellow or black, and larger than 

 the ordinary green form. 



Another form, common everywhere on mouldy food of all 

 kinds, as well as in other situations, is the blue mould (Peni- 

 cillium). This, in general appearance, resembles almost exactly 

 the herbarium mould, but is immediately distinguishable by a 

 microscopic examination (Fig. 42, 6r). 



In studying all of these forms, they may be mounted, as directed for 

 the black moulds, in dilute glycerine ; but must be handled with great care, 

 as the spores become shaken off with the slightest jar. 



Of the larger Ascomycetes, the cup fungi (Discomycetes) may 

 be taken as types. The spore fruit in these forms is often of 

 considerable size, and, as their name indicates, is open, having 

 the form of a flat disc or cup. A brief description of a com- 

 mon one will suffice to give an idea of their structure and 

 development. 



Ascobolus (Fig. 43) is a small, disc-shaped fungus, growing 

 on horse dung. By keeping some of this covered with a bell 

 jar for a week or two, so as to retain the moisture, at the end 

 of this time a large crop of the fungus will probably have 

 made its appearance. The part visible is the spore fruit (Fig. 

 43, A), of a light brownish color, and about as big as a pin- 

 head. 



Its development may be readily followed by teasing out in water the 

 youngest specimens that can be found, taking care to take up a little of 

 the substratum with it, as the earliest stages are too small to be visible to 

 the naked eye. The spore fruits arise from filaments not unlike those of 

 the mildews, and are preceded by the formation of an archicarp composed 

 of several cells, and readily seen through the walls of the young fruit 

 (Fig. 43, B). In the study of the early stages, a potash solution will be 

 found useful in rendering them transparent. 



The young fruit has much the same structure as that of the mildews, 

 but the spore sacs are much more numerous, and there are special sterile 

 filaments developed between them. If the young spore fruit is treated 

 with chlor-iodide of zinc, it is rendered quite transparent, and the young 



