The fertile portion when examined under the microscope is found to bear little 

 sack-like bodies called perithecia. In most Cordyceps the perithecia are imbedded 

 in the tissue (stroma), only the mouths reaching the surface. Some species, how- 

 ever, have the perithecia exserted, and they are borne on the surface of the stroma 

 (free) in some species. Our figure 625 is an ideal drawing, though the head of a 

 Cordyceps showing the perithecia as little sacks. Fig. 611, a section enlarged of a 

 Cordyceps club, shows the perithecia as dark spots around the margin. 



Each perithecium contains numerous long thread-like hyaline bodies. Under 

 a low power they appear as simple threads, but under a high power are resolved 

 into linear sacks (asci) each containing eight linear septate spores. The bundle of 

 spores completely fill each ascus, and the walls of the ascus are so hyaline and thin 

 they are difficult to see. The spores are septate in the ascus, and in water mount 

 break up into their component cells, which are called secondary spores. Each spore 

 breaks up into many, 120 or 160 secondaries. Some species have the spores tardily 

 septate, and appear in the ascus as long threads, and it has been stated (erroneously) 

 that there are species with non-septate spores. Other species have the spores at an 

 early period, broken up into the little segments in the ascus. Fig. 612 is an ideal 

 drawing of the top of an ascus highly magnified, showing the linear spores divided 

 by septae. 



Fig. 613. 



Isaria farinosa. 



Fig. 614. 



Cordyceps militaris. 



Supposed to be the conidial and perfect form of the same species. 



The life history of Cordyceps is not known, excepting as to the common species 

 of Europe, Cordyceps militaris, which was first investigated by Tulasne, and after- 

 wards by de Bary. It is probably, however, that the development of all the species 

 is about the same. The spores become attached to the moist body of a caterpillar 

 (or other insect) and germinate, sending out germ-tubes which penetrate the thin 

 outer skin of the host. Here they enlarge and take the nature of fungal hyphae, 



4 



