222 DISEASES OF FIELD & GARDEN CROPS. [CH. 



us, and the problem presents itself for solution How do 

 these inconceivably minute hairlike bodies or sporidia 

 free themselves from the asci and perithecia of the 

 Claviceps, and cause ergot in grasses ? 



If germinated ergots are kept in moist air under a bell 

 glass and observed against a black background in sun- 

 shine, the ejection of the spores like shining needles or 

 almost invisible glittering arrows may be clearly seen 

 with a lens. What power it is that causes the discharge 

 from the flasks no one has at present certainly explained ; 

 but the phenomenon is well known to occur in many 

 fungi. The discharge takes place after a sudden touch 

 or movement, or on a change of light or temperature, as 

 when a sunbeam suddenly falls on any ascus- bearing 

 fungus. The glittering hairlike spores are shot from the 

 mouths of the perithecia into the air radially in all 

 directions. The sporidia may be easily caught and 

 examined if strips of glass are smeared slightly with 

 glycerine and placed under a bell glass near the ripe 

 fungi. The sporidia can then be examined whilst alive 

 and fresh. The asci as well as the free sporidia are 

 often expelled, and it frequently happens that the act of 

 expulsion is too weak to propel the sporidia or asci into 

 the air, and they hang only half expelled from the mouths 

 of the perithecia. 



If we now suppose ourselves to be in a district where 

 rye is common, and where rye was ergotised during the 

 previous autumn, we shall have the rye in flower at 

 the precise time when these myriads of glittering little 

 needle-like sporidia are sailing through the air. Such 

 needle-like spores as do not light upon flowering grasses 

 perish ; but where there are so many millions of sailing 

 spores some must of necessity fall upon the flowers of a 

 grass let us say rye. 



We must now imagine a needle-like sporidium falling 

 close to the pistil and stamens, and reaching the base of the 

 pistil of a flower of rye. Here the spore bursts or germi- 



