72 SUMMARY OF CURRENT RESEARCHES RELATING TO 



forms he worked with were Sordaria pinicola, Neotiella albocincta, and 

 Hydnooolites sp., an underground fungus. Many other forms were 

 examined, and the results are summarised. He finds that the asci bud 

 out from the penultimate cells of the ascogenous hyphse only in some 

 forms ; in others, as in Sordaria pinicola, they rise from the terminal 

 cell ; in a few species they rise apparently from any cell. 



In every case that was definitely determined there was fusion of two 

 nuclei in the young ascus ; the conjugating elements, though not sisters, 

 might be the daughters of sister-nuclei. Bodies corresponding to 

 Guilliermond's metachromatic corpuscules were noted in the ascus. 

 They disappear before the spores are matured. The spindles were found 

 to be of intranuclear origin, the centrosomes and asters of extranuclear 

 origin. The chromosomes vary in number for different species from four 

 to eight. The spores are delimited by a plasma membrane directly after 

 the last mitosis in the ascus. The nucleus, after it has acquired a wall, takes 

 a pear-shaped form with a beak, the centrosome being at the beaked end. 

 The formation of the spore membrane begins at the centrosome end of 

 the nucleus, and develops towards the opposite pole. An outer second 

 membrane is also formed, and lies against the surrounding epiplasm. 

 Retraction of the beak follows after the wall is completed, and the 

 nucleus assumes its spherical form. There was no evidence to support 

 Harper's finding, that the astral rays fused to form the spore membrane ; 

 they were constantly seen within the spore and apart from the wall. 

 Within the spores karyokinesis may take place, with or without the 

 formation of septa, according to the species of fungus. In Podospora 

 an enucleated, elongate part of each spore is cut off, the nucleus passing 

 to the end of the spore where septation takes place. 



The writer discusses at length the bearing of these facts on the 

 origin of the Ascomycetes. ' He concludes that the phenomena of 

 spore-formation, as discovered by him, are not incompatible with the 

 view that homologises the ascus with the oomycetous zoosporangium. 

 Though there is undoubted nuclear control in the formation of the 

 spores in the ascus, even the shape of the nucleus changing in the 

 process, there is probably nuclear control also in the Zygomycetes and 

 Oomycetes, where the cleavage masses are always nucleated. Faull 

 claims that his observations " indicate that the process of delimitation of 

 the spores is practically the same in both cases — a cleavage, — and that 

 the plasma membranes of the spores are the same." He thinks possibly 

 the Ascomycetes may have arisen from some such phycomycetous 

 group as the Peronosporinese or Saprolegniineae. 



Observations on Claviceps purpurea. * — C. Engelke has been 

 making a series of culture experiments with ergot, and states that he 

 was unable to obtain cultures from the conidia of the fungus. He 

 secured spores that were ejected from the perithecia, and with these he 

 obtained a pure growth with which he was able to inoculate rye plants. 

 Infection only took place before pollination, and only on the stigma. 

 There was no infection through the stomata. Honey-dew is entirely 



* Jahresb. Nat. Ges. Hann., 1905, pp. 70-2. See also Ann. Mycol., iii. (1905) pp. 

 377-8. 



