INTRODUCTION TO THE STUDY OF FUNGI 



There is another condition which the mycelium of some 

 Fungi assume that is something of a resting stage, and in 

 former days these were classed under a genus called Sclerotium. 

 They are in the form of hard, compact, irregular nodules, from 

 the size of a pin's head to that of a child's head, according to 

 the species. They are mostly dark coloured externally, and 

 nearly white and horny within, with a firm cellular substance. 

 We will conmience with one that is well known, under the 

 name of Ergot, and occurs on the spikes of rye, wheat, and 



many grasses, converting the 

 ovary into a Sclerotium, or 

 replacing the ovary with a 

 Fungus growth, whichever 

 view pleases best. These 

 abnormal growths are three 

 times as long as the ordinary 

 seed of the rye or grass, 

 elongated, and a little curved, 

 so that they look like a horn 

 or spur projecting from the 

 ear of grain. If a thin slice 

 of the substance is placed 

 under the microscope, it will be seen to consist of a densely 

 compact mass of cells, somewhat irregular from mutual pressure, 

 with thick walls and rather oily contents. At last they are liable 

 to become dissociated from the spike, and fall to the ground, 

 where they will lie quiescent and unchanged through the winter. 

 When spring arrives, active vitality recommences, and the sclero- 

 tium germinates by producing one, two, or more — generally several 

 — little slender twisted stems, with a globose head, reminding 

 one of a pin. The stem is whitish, and the head of a pale purple. 

 It is within the globose head that the fructification is produced. 

 This latter is the mature Fungus of the Ergot sclerotium, and 

 is then called Claviceps jmrpurea, one of the Sphaeriacei (Fig. 2). 

 By way of illustration, we have indicated briefly the history 

 and development of the Ergot sclerotium, but it will scarcely 

 be consistent with the design of this chapter to repeat the 

 process for other species. Another example may be found 

 inhabiting the dead haulms of potato. . First of all the haulms 



FiQ. 2. — Ergot Sclerotia germinating. 

 After Tulasne. 



