iv] PEZIZALES 109 



At this stage a large, more or less oval sac is often found to be continuous 

 with the terminal, or receptive, cell of the trichogyne into which a proportion 

 of its contents pass (fig. 6$6). There seems no doubt that this sac is the 

 antheridium, but its development is not known, and there is no evidence 

 that its contents ever pass beyond the receptive cell of the trichogyne. 

 Indeed all the a\ ailable evidence shows that both antheridium and trichogyne 

 are now merely vestigial structures. 



Nevertheless the development of the oogonium continues, its nuclei 

 increase to something over 500 in number, and ascogenous hyphae bud out. 

 Before passing into these the oogonial nuclei fuse in pairs, so that normal 

 fertilization is here replaced by the union of female nuclei. The ascogenous 

 hyphae branch and give rise to asci, in each of which eight spores are 

 produced in the usual way. The karyokinetic figures are small but very 

 clear, there are four chromosomes in the first and second divisions, but in 

 the third telophase only two have been recorded. There is some evidence 

 that the chromosomes show regular and characteristic differences of form, 

 which reappear in successive divisions. 



The peridium, though much better developed than in the Pyronema- 

 ceae, is never completely closed, as in Humaria or Ascobolns, across the 

 top of the ascocarp. The paraphyses are numerous and contain orange 

 granules. 



Lachnea scutellata occurs on decaying wood, forming bright red apothecia. 

 The archicarp consists of seven to nine cells, the subterminal of which 

 enlarges to form the oogonium. The nuclei in this cell divide, and, according 

 to Brown, show five short, stout chromosomes. He did not observe nuclear 

 fusion or association in the oogonium, but regards the nuclei lying in contact 

 as the two daughter nuclei of a single mitosis. Large ascogenous hyphae 

 develop, undergo septation, and branch freely. Their tips bend over and 

 asci are formed in the usual way from the penultimate cells. The terminal 

 cells may undergo further growth and give rise, as in several other Disco- 

 mycetes, to new asci. Nuclear fusion takes place in the young ascus, and is 

 followed by a meiotic reduction. Five gemini are recorded, but, in the 

 anaphase of the first division, ten chromosomes travel towards each pole. 

 This Brown takes to indicate an early fission of the daughter chromosomes. 

 In the second and third divisions five chromosomes are seen throughout. 

 Brown infers the occurrence of a single fusion in this species, that in the 

 ascus, and a single reducing division 1 . 



Lachnea cretea has a pale buff apothecium, beset with hairs (fig. 66a). 

 It has been found on plaster ceilings, and, like many other saprophytic 

 species, grows readily in artificial culture. 



1 The magnification of Brown's figures of the divisions in the oogonium is enormous (x 11,100), 

 and their details should therefore probably be received with some caution. 



