342 SUMMARY OF CURRENT RESEARCHES RELATING TO 



perforations through which the nuclei pass to enter the ascogenous 

 hyphffi. (o) The ascogenous hyphse do not in this case constitute a 

 Bynkaryophytic system. (4) The asci arise from the subterminal cells 

 of the recurved tips of the ascogenous hyphje, which cells are binucleate ; 

 these hyphse are profusely branched, and develop considerably before 

 becoming septate. (5) The ascus nucleus is formed by the fusion of 

 the two primary ascus nuclei ; it enlarges as the ascus grows. (6) It 

 then divides by triple division to form eight free nuclei, each of which, 

 after a period of rest and growth, undergoes further division, until 

 thirty-two free nuclei are formed in the ascus. (7) Spore delimitation 

 follows, the astral rays bending over and fusing to form a spore mem- 

 brane. (H) Each spore is one-celled and uninucleate. (9) The endo- 

 spore becomes more granular and hyaline as the spore develops, and the 

 outermost portion of the hyaline gi-anular area constitutes the exospore. 

 (10) No evidence has been found to support the theory that the ascus 

 is homologous with the sporangia of either the Oomycetes or the Phyco- 

 mycetes. (11) The formation of the large number of spores is evidently 

 an adaptive phenomenon, and does not interfere with the conception 

 that the ascus is a spore-mother-cell. Overton traces an alternation of 

 generations in this as in other Ascomycetes — the sporophyte including 

 the ascogenous hyphs and the asci up to the time of the reduction 

 division (one of the divisions in the ascus), which initiates the gameto- 

 phyte generation. He adds that ascospores which are septate have 

 apparently begun an intrasporal germination, the gametophyte forming 

 consideralale embryonic tissue within the old spore-wall. 



Witches' Brooms.* — James Saunders has recorded his observations on 

 these deformations on trees in the tract of country that lies around Luton. 

 The brooms, though usually due to Exoascus, a parasitic fungus, may 

 also arise from the irritation caused by insects, or by "gnarling," i.e. an 

 excessive development of leaf -buds on the branches or main stems. The 

 writer confines his attention to those brooms that are caused by fungi. 

 He describes the particular cases that he has noticed, and the appearance 

 of the abnormal growth. On cherry and wild cherry the effect is the 

 same : the leaves on the diseased branches are red and crumpled. Three 

 cases on hawthorn are described : the branching of the brooms was 

 different from the rest of the tree, and many of the twigs were strangely 

 distorted. A l:»room was also found on an elder-tree. Others grew on 

 the elm, probably caused largely by gnarling. Birch-trees, horn- 

 beams, and hazels were found with similar growths due to the fungus. 

 Brooms were also found causing deformations on spruce-fir and silver- 

 fir. They were caused by forms of Uredineffi. 



A series of observations was made as to the unfolding and fading of 

 leaves on the brooms, and it was found that though, in some cases, the 

 leaves came earlier than on the normal branches, they always faded 

 earlier. An acceleration of development accompanied by diminished 

 vitality is generally characteristic of all these abnormal growths. 



Hypocreaceae and Scolecosporeae from Java.f — M. Raciborski re- 

 marks that he found no form of Claviceps on grasses in Java, but that 



* Trans. Herts. Nat. Hist. Soc, xiii. (1907) pp. 67-78 (3 pis. and 1 fig.). 



t Bull. Acad. Sci. Cracovie, Classe Sci. Math.-Nat., x. (1906) pp. 901-11 (2 pis.). 



