SPORE DISCHARGE AMONG ASCOMYCETES 191 



arranged into spore-liberation types [Ingold (1933)]. In the first 

 type are species of Chaetomium, Ascotricha, Daldinia, and Dia- 

 trype and Ceratostoviella fimbriata. Their ascus wall is very deli- 

 cate and ephemeral, and as a consequence the ascospores are freed 

 and lie intermixed with gelatinous material within the perithecial 

 cavity. The gelatinous material absorbs water readily and swells, 

 and the spore mass is squeezed out through the ostiole, like tooth- 

 paste from a tube. 



The second type, first correctly described by Zopf [de Bary 

 (1887)], occurs in Sordaria and Podospora and certain other 

 coprophilous species, which develop on the dung of herbivorous 

 animals [Griffiths (1901)]. The perithecia are pear-shaped, and 

 the ostiolar canal is lined with hyphae directed toward the open- 

 ing. The perithecial walls are thin enough for spore discharge 

 to be satisfactorily observed. Ingold (1939) mounted entire 

 perithecia of Podospora curvula in water in a hanging drop 

 and noted that they contain asci in different stages of maturity. 

 The asci and interspersed paraphyses are attached to a stroma 

 occupying the bottom of the perithecium and remain attached 

 to this stroma during discharge. On looking through the peri- 

 thecial wall, the observer may note that mature asci elongate by 

 growth and by the pressure exerted by the surrounding cells. 

 The greatly distended elastic ascus extends into the neck canal, 

 and the ascus tip slips through, being "lubricated" by the hyphae 

 within the canal, until it protrudes slightly beyond the ostiole. 

 At this stage the tip of the ascus opens by a circumscissile rup- 

 ture, and the cap formed, together with the mass of 8 ascospores 

 and much of the ascus-sap, is shot upward. Immediately after 

 discharge the empty ascus, being attached to the basal stroma, 

 snaps back inside the perithecium, and another ascus elongates, 

 opens, discharges, and is withdrawn seriatim, until the perithecial 

 content is exhausted. Since each ascospore of P. curvula possesses 

 two terminal gelatinous appendages that become entwined, the 

 spore mass is a rather large projectile and can be hurled for a dis- 

 tance of 20 cm or more. The neck of the perithecium being 

 phototropic, the ascus content is discharged directly toward the 

 source of li^ht. 



The third type has asci of "jack-in-the-box" construction, as 

 aptly designated by Ingold (1933). This type has many variants, 

 but in each kind the elongated ascus extends to the exterior of the 



