CHAPTER III. — SPORES OF FUNGI. 



91 



Section XXIII. The process of ejection in the Pyrenomycetes which discharge 

 their spores simultaneously was first correctly described in Sordaria by Zopf 1 . 

 Numerous asci placed upright side by side in a thick tuft fill the swollen enlarged 

 basal portion of a flask-shaped receptacle, the perithecium, which is continued upwards 

 into a more or less elongated neck. In large forms, as S. fimiseda, the neck is more 

 than a millimetre in length but much shorter in the smaller species, and is traversed 

 longitudinally by a very narrow canal, not so broad as an ascus, which enlarges into a 

 conical form at its inner end above the group of asci and is open to the air above at the 

 outer end. Till the spores begin to ripen the asci are between narrowly cylindrical 

 and club-shaped, and of the same height as the basal 

 ventral portion of the perithecium. Then they begin to 

 elongate one after another while they grow much broader 

 at the apex. The only direction in which they can 

 elongate is that of the canal of the neck. When the apex 

 of the first ascus reaches the inner end of the canal, it 

 enters it and swelling there to a broadly club-shaped 

 form, and causing a corresponding enlargement of the 

 canal, it continues to lengthen, till its apex is on a level 

 with the outer mouth of the canal or a little above it ; 

 then its ejection takes place. Then the next ascus enters 

 into the now empty canal, and so on one after another. 

 The lower extremity of the ascus continues attached to 

 its original point of insertion at the base of the peri- 

 thecium until ejection. The elongation is therefore very 

 considerable; in the case depicted in Fig. 44, for instance, 

 it is more than six times the length attained by the ascus 

 at the time the spores are ripe, and is at least three times 

 that length beneath the widened upper part. The lower 

 portion seems to become narrowed at the same time 

 under the pressure of the neighbouring asci which are 

 beginning to swell, but it is difficult to be quite certain on 

 this point on account of the strong lateral pressing to- 

 gether of the parts. 



a dense group of asci, most of them with 



The rapidity with which the elongations are accom- ripe spores; above tws group are other 



mature asci in various stages of elongation 



plished is comparatively small. In a small specimen preparatory to ejection, the uppermost 



having almost reached the opening of the 



observed in water the movement of the apex about a neck - Ma s^- about io ° times - 

 spore's length ( = 17 n) occupied some 15 minutes, and 



the passage through the whole neck about 8 hours. In the specimen of Sordaria 

 minuta(?) given in Fig. 44 the motion was quicker, a spore's length of 10 /x requiring 

 some five minutes. How far light, heat and other external causes accelerate or 

 retard the movement, and what are the specific differences which certainly exist, 

 are points which have yet to be investigated. 



Section XXIV. The force with which the spores are ejected does not appear 

 to be great. In Bulgaria inquinans and Protomyces macrosporus they are sent straight 



Fig. 44. Sordaria minuta, Fuckel (J). 

 Form with 4-spored asci ; small perithe- 

 cium grown on a microscopic slide and 

 observed in the living state lying in the 

 culture-fluid, in optical longitudinal sec- 

 tion ; at the base of the perithecium is 



1 As cited on p. 8$. 



