On the sexuality and development of the ascocarp of Humaria granulata quél

Abstract

The observations of Harper (15, 16, 17) on Sphœrotheca, Erysiphe and Pyronema , have clearly shown that some at least of the Ascomycetes exhibit an ordinary sexual process. It is true that attempts have been made by Dangeard (10) to refute Harper’s observations, and doubt has been cast on his work by Lindau (22), Holtermann (18), and other; but the recent very convincing work of Claussen (8a) on Boudiera , together with the strong circumstantial evidence obtained by Barker (1 and 2) in Monascus and Ryparobius , by Miss Dale (9) in Gymnoascus , and by Baur (3, 4), and Darbishire (10a) in lichens, and, also, the confirmation by ourselves (7) of Harper’s work on Sphœrotheca , leave no doubt that the sexuality of the Ascomycetes is founded on a firm basis. The earlier non-cytological observations of a number of forms, however, have shown clearly that the existence of a normal sexual process can hardly be expected in all the Ascomycetes. For example, in Melanospora parasitica Kihlmann (20) observed the development of the archicarp into the perithecium without the intervention of an anteridium; in Chœtomium , Oltmanns (24) found that the anteridium was usually absent; in Ascobolus , the earlier observations of Woronin (25) and Janczewski (10), and the later observations of Harper (16), brought to light no definite anteridium. Again, among the lichens, according to the observations of Fünfstuck (13), in Peltigera and Peltidea the ascogonia are without trichogynes; and Solorina saccata , according to Baur’s (4) researches, seems clearly to develop without any ordinary fertilisation. It is obviously, then, very desirable that the cytology of some member of the Ascomycetes, the ascocarp of which develops without fertilisation by an anteridium, should be carefully investigated. The form here studied is of this type and hence is of peculiar interest.