THE FUNGI : ASCOMYCETES AND BASIDIOMYCETES 285 



Economic Importance of Ergot 



The occurrence of ergot in rye bread may have serious consequences, 

 causing gangrene and loss of hair, teeth and nails. Cattle eating ergot grain 

 may show gangrenous and nervous symptoms with the loss of hoofs, tails 

 and horns, and miscarriage of young. Ergot poisoning, known as Ergotism, 

 is very dangerous, the mortality being as high as 50 per cent. 



Ergot is chiefly collected in Spain, Portugal, Poland and Russia, either 

 by hand picking or by threshing through a special machine. Ergot contains 

 Ergotamine and Ergotoxin, and is used medicinally to induce contraction 

 of the smooth muscles, especially of the uterus in childbirth, and to control 

 uterine haemorrhage (see Volume IV, Economic Botany). 



Ergot contains, in addition to the above toxins, the substance acetyl 

 choline, which causes muscular contraction in dilutions as high as i part 

 in 500 millions. Acetyl choline is responsible for normal muscular con- 

 traction, being formed at the junction of the motor nerves and muscles, 

 where it lasts for only a fraction of a second, producing contraction before 

 it is destroyed by the enzyme cholinesterase. If its action is prolonged it 

 causes paralysis. 



Artificial infection of rye has been successfully accomplished in Vienna 

 and also in Australia, though it still remains to be seen whether this can be 

 done on a commercial scale. 



Sphaeriales 



The Sphaeriales are Ascomycetes in which the ascospores are produced 

 in flask-shaped perithecia which are free or immersed in dark-coloured 

 membranous or corky stromata. When the perithecia are immersed in a 

 stroma they retain a distinct wall. Asexual reproduction is by conidiospores. 



The group is a very large one ; the majority are saprophytes and are 

 responsible for bringing about primary decay of plant tissues. Many produce 

 leaf-spots, and it is only among the higher members that a large independent 

 fruiting body is produced. This fruiting body may vary greatly in form from 

 a spreading crust somewhat similar to a leaf-spot, to a spherical mass, while 

 in a few examples the fruiting body consists of a simple or branched body of 

 quite considerable size. 



In such forms perithecia are developed just below and at right angles to 

 the surface of the stroma, but it frequently happens that the asci are developed 

 in cavities identical in shape to the perithecia, but in which chains of coni- 

 diospores had been previously produced. On the other hand, conidia may 

 arise superficially both on the surface of the fruiting body and also on the 

 mycelium itself. In the former position they may give a characteristic colour 

 to the fruiting body. 



We shall select as our example Hypoxylon coccineum, belonging to the 

 Xylariaceae, the highest family of the Sphaeriales. 



