WHITE MILDEWS OE BLIGHTS. 



167 



tioned above^ and carefully look at them with a 

 pocket lenSj little black points^ almost as small as 

 a pin-pointj or more resembling the full stop with 

 which this sentence closes^ will be found scattered 

 over the white threads. The aid of the microscope 

 must be again sought to make out the structure of 

 the little black dots. Closely nestling upon the 

 mycelium^ the little points will prove to be sphe- 

 rical brownish conceptacleSj surrounded with trans- 

 parent floccose appendages. Many other species 

 are far more beautiful than that of the grass-leaf, 

 as will be seen by reference to our plate. The 

 variation consists chiefly in the form of the 

 appendages which spring from the conceptacle 

 and surround it in a radiating (as ui figs. 219^ 

 222, 225, and 230), or in a more or less confused 

 and entangled manner (as in figs. 216, 240, 245, 

 and 251). The surface of the conceptacle is mi- 

 nutely reticulated, and its base is attached to the 

 mycehum. When first formed, these globose con- 

 ceptacles are almost colourless; they afterwards 

 acquire a yellow colour, and are ultimately of a 

 deep brown. The appendages are seldom at aU 

 coloured. Within the conceptacle are contained 

 from one to several transparent obovoid sacs, or 

 spore-cases, called sporangia, enclosing a definite' 

 number of spores (figs. 218, 224, 228, &c.), which 

 vary in different species. In the hazel mildew, for 

 instance, there are two spores in each sporangium ; 

 in the willow mildew four ; in the maple mildew 



