248 COMPARATIVE MORPHOLOGY OF FUNGI 



rest period of several months duration; but they are not independent in 

 form, rather dependent to a high degree on the limits of their substrates. 



This growing dependence of the sclerotia is shown in the Brazilian 

 Claviceps lutea and C. ranunculoides. In C. lutea on Paspalum sp., the form 

 of the sclerotia is still influenced by the substrate, but is much more 

 independent than in C. balansioides, while in C. ranunculoides on Setaria, 

 the sclerotia have become entirely independent of substrate and are 

 able to form specific structures. In the young stage, their peripheral 

 hyphae cut off orange-red conidia which disappear during the formation 

 of the sclerotial rind. 



The high point of this series is formed by C. purpurea and by Ustilagin- 

 oidea, differing chiefly in their imperfect forms. The Asiatic Ustilagin- 

 oidea Oryzae changes the ovaries of rice to pseudomorphs which cut off a 

 large number of brown gemmae. These were earlier considered the smut 

 spores of Ustilago virens. Although the perfect form of this species is 

 unknown, the author believes that the resting over of the dry period by 

 these gemmae suggests its relation to Ustilaginoidea, because in the South 

 American species with the same gemmae, U. Setariae on Panicum Crus- 

 ardeae (Setaria Crus-ardeae), true sclerotia are formed which, after a 

 resting period, germinate with perithecial heads. 



Claviceps purpurea, or ergot, is parasitic on various grasses, particu- 

 larly rye. At flowering the ascospores infect the ovaries; which are 

 permeated except at the tip by mycelium and transformed into dirty 

 white, soft, furrowed pseudomorphs. On the surfaces of the fur- 

 rows, the compact hyphal ends form a large number of small, unicellular 

 hyaline conidia (Fig. 162, D) which, embedded in a sweet liquid, drop 

 from the spikelet; they were described as the Imperfect Sphacelia segetum. 

 Dissemination takes place by insects, occasionally also by rain and wind. 

 They retain their ability to germinate and infect for more than one year 

 (Stager, 1912; Bonns, 1922). When this form of fructification has been 

 exhausted, the body of tissue changes acropetally into a horny sclerotium 

 which, because of a strong intercalary growth, projects out of the ear and 

 is differentiated into a dark violet, rimose, pseudoparenchymatous rind 

 and a prosenchymatous ground tissue. At its top, the hyphae of the 

 Sphacelia stage grow luxuriantly; finally, they also dry and form a little 

 cap at the tip of the sclerotia which contains the entangled and dried 

 stamens and stigmas of the original flower (Fig. 162, C). When the 

 life cycle of Claviceps purpurea was still unknown, this sclerotium was 

 called Sclerotium Clavus. On drying, this becomes as hard as stone and 

 forms the ergot or secale cornutum of the pharmacopoeia (Fig. 162, B). 

 At maturity, the rye spikelets fall to the ground and winter over there 

 in case they are not spread by man with the grain. 



In the spring, with sufficient dampness, germination begins. Certain 

 parts under the rind (in large kernels 20 to 30 of them) become rich in 



