THE PIvANT WORI.D 173 



Those who are looking- for a fertile field for research can here find 

 problems in abundance, either biologic or toxonomic. Of the ten thousand 

 or more species which have been described, the complete life history of 

 perhaps less than one hundred is known. In regard to our systematic 

 knowledge of them Dr. Underwood has very truly said that "there is 

 scarcely a genus that is not in crying need of a revision." 



The majority of these plants are considered saprophytic — that is, the 

 form which produces asci occurs on dead animal or vegetable matter. 

 Many which are now classed as saprophytic apparently pass the early 

 stages of their life as parasites. The name Pyrenomycetes — which is 

 derived from two Greek words, pyren, meaning the stone of a fruit, such 

 as an olive, and mycetes, a mushroom or fungus — was first applied to 

 these plants by the distinguished Swedish mycologist EHas Fries in his 

 great work on fungi entitled " Systema Mycologicum " (1821-29), which 

 was intended to include in its three small volumes descriptions of all the 

 fungi which had been described at that time. Some idea of the rapid 

 increase in our knowledge of these forms of life may be gained from 

 the fact that Saccardo in the sixteen bulky volumes of his ' ' Sylloge 

 Fungorum " has not yet included all the species described. 



But to return to the Pyrenomycetes . They constitute one of the chief 

 divisions of the great group Ascomycetes, and may be distinguished from 

 other ascus-bearing forms, such as the cap fungi, by the perithecium, the 

 globular or flask-shaped body in which the asci or spore sacs are enclosed. 

 These perithecia usually open by means of a pore at the apex, which is 

 called an ostiolum (little mouth), in order to permit the escape and 

 distribution of the spores which perform the function of reproduction and 

 are analogous to the seeds of the flowering plants. The perithecia are 

 mostly small and dark-colored. They rarely exceed one-sixteenth of an 

 inch in diameter, and most are half that size or less. When occurring 

 singly, as they do in many genera, they are not so easily noticed as when 

 they occur in groups or masses, as they frequently do. In the genus 

 Hy poxy Ion, the perithecia are arranged on a stroma or matrix, forming 

 more or less globular masses, varying in size from that of a pea or 

 smaller to a hickory nut. This genus is very common, and specimens 

 can be found at almost any time on old fallen branches of various decid- 

 uous trees, especially alder and birch. If one cut a section of one of 

 these with a pocket-knife he will be able to distinguish the separate 

 perithecia which form a layer about the mass. 



Many forms produce their perithecia beneath the bark and can only 

 be detected by the slight pustular elevation of the bark or by the groups 

 of minute black mouths which protrude slightly. To study the spores the 

 compound microscope is necessary, but good instruments are becoming 

 so cheap that few botanists, even amateurs, can afford to be without one. 



