270 PROKESSOll MOHL ON 



is changed into a cellular knot, whose white hue soon passes into 

 yellow, and at a later period into brown, and that from these 

 superficial cells the thread-like appendages are developed. 

 Though these forms of fruits are so extremely different at first 

 sight, a number of intermediate forms occasionally though rarely 

 are developed. These possess the regular globose form, and in 

 part also the size of the Erysiphoid fruit, and are sometimes 

 though not always furnished with similar articulated hairs, while 

 the articulated filiform appendage is wanting at their apex ; on 

 the other hand they have the same yellow-brown colour, the thin 

 minutely-cellular membrane, and the same small spores mixed 

 with gum as the Cicinoboloid fruit. 



Apart from the morphological interest which this form pos- 

 sesses as intermediate between two such different organs, its 

 occurrence is the more important because it contradicts most 

 undeniably the objection which may so easily be made, that tlie 

 Erysiphoid fruit does not belong to the mycelium from which the 

 Cicinoboloid springs, but is seated parasitically upon it ; an 

 objection which repeatedly deceived me in the beginning of my 

 investigation before I was convinced to the contrar3^ 



In Erysiphe lamprocarpa growing on the leaves of Plantago 

 major, I constantlj'^ found similar intermediate forms, but always 

 having filiform appendages. The Cicinoboloid fruit appeared first 

 on the Vine-mildew towards the end of August, at which time it 

 overran in extraordinary profusion the yet unripe berries, and in 

 some measure the leaves also. It was not developed (as is the case 

 also in all other species of Erysiphe) in those parts of the Vine 

 where the fungus exhibited a very vigorous vegetation, and their 

 oval conidia fell off in great abundance, and which were in con- 

 sequence of a snowy white, inasmuch as the exuberant development 

 of the organs of vegetation proves an impediment to the formation 

 of the organs of fructification. The fruit does not commonly arise 

 as in the Hop-mould from one of the lowest cells of an upright or 

 penultimate thread, but mostly from a terminal cell ; frequently 

 also two or three cells contribute to the formation of a single fruit, 

 or the preceding joint, though retaining its original form, is filled 

 with spores. My microscope was not sufficiently powerful to 

 ascertain perfectly the history of the development of the fruit. 

 At first a yellow finely-granular protoplasm was formed in the 

 cells destined for fruit, in which the granules became gradually 

 more distinct, and the spores capable of being recognised, even 

 before the cells which form the membrane of the sporangium were 



