6 PROFESSOR VON MOHL 



The tlireads of the Mycelium* creep constaully iu a horizontal 

 direction, adhering most accurately to the cuticle. While these 

 are yet at a considerable distance from one another (Fig. 1) we 

 perceive that they are branched in a pinnate manner ; and since 

 these branches are repeatedly divided in the same manner, in 

 consequence of their crossing, the whole assumes the appearance 

 of a net, which in a short time loses its regularity from the in- 

 cursion of neiglibouring threads. They have in consequence a 

 tendency to adhere not only to the matrix, hut also to each other 

 (Fig. 3) where they cross ; so that except strong magnifying 

 powers be used, an appearance arises as if the branches were 

 far more numerous and irregular than they are in reality. 



In the older portions of the threads which lie in the middle of 

 the fungal spots, the fructifying branches begin to show them- 

 selves at a very early period, springing out on their upper side 

 in a vertical direction, but not always perfectly rectilinear. While 

 the creeping threads are divided into long articulations by distant 

 and obscure septa, the upright threads are always distinctly jointed. 

 They pass from a tolerably cylindi'ical to a clavate form (Fig. 4) 

 showing a greater quantity of protoplasm iu the upper cells, but 

 especially in tlie last, Tliis at a later period swells out into an 

 oval form, and is separated by a distinct septum, a greater or less 

 number of little vacua being first formed in the protoplasm 

 (endochrome). During the past spring, I found almost without 

 e.xception, only a single oval utricle at the tip of each thread, 

 whereas in the autumn of 1851, two or three were generally pre- 

 sent, forming a little necklace. I have already remarked in my 

 former treatise, that the size of these fallen utricles is subject to 

 great variation, and must therefoi-e be used with some circum- 

 spection in the distinction of species. 



The connection of the fungus with the matrix is, as was before 

 mentioned, of especial moment as regards the theory of the 

 disease. To make this connection clear, we must examine the 



* The investigatiou of the Mycelium must be mtide with light reflected 

 from above, for which purpose nothing is better than Lieberkiihn's mirror. 

 It is self-evident that such spots must be cho.sen as are protected from 

 evei-y cause of injury, or otherwise the tender threads will infallibly be 

 damaged. It appear.s probable that this simple and obvious jn-ecaution 

 has been neglected by Trevisan, who asserts with much earnestness (Sulla 

 origine delle alterazioni clie osservansi alia superficie delle parti verdi nelle 

 viti affette dal bianco dei grappoli. Osservazioni di Vittore B. A. Trevisan. 

 Padova, Obtobre, 1852), that fungi never grow on the sound cuticle, but 

 always on already diseased patches. 



