272 



RESEARCHES ON FUNGI 



to one or more diploid fruit-bodies ; and, as a fruit-body 

 develops, conjugate nuclear division continues. At last, a con- 

 jugate pair of nuclei becomes cut off in each basidium (Fig. 143, 

 No. 1) and then conjugate nuclear division ceases. In each 



0=(a,W ®=(aB) 



YiG.US.-Copnnu, lagopu^s. Diagram showing the completion of the sexual 

 process in a basidiimi, including the fusion of the two members of a conjugate 

 pa^r of nuclei, the two successive divisions of the fusion nucleus, and the 

 formatln of fmir haploid nuclei, one of which enters each fJ^^JlllZTin 

 The sexual constitution of each haploid nucleus is indicated by s^^^ding in 

 accordance with the scheme shown on the upper left No. 1 : a youj^g bag 

 dium containing a pair of conjugate nuclei (AB) and («6). No. 2 . the (AH) 

 anTthe (U) nSclei^have fused f the diploid nature o '^^^'^^^J^l'^^^ll 

 Ldicated by cross-hatching. No. 3: the fusion nucleus has undergone its 

 firs 5 vfsion ; the daughter nuclei, like their parent, are diploid as indicated 

 bv the cross-hatching. No. 4 : the two daughter nuclei of the fusion nucleus 

 have div ded ; thi Lond division of the fusion nucleus was accompanied by 

 the reduction of the chromosomes to one-half their number (presuniably), and 

 bJ^he segregation of the sex factors; the four resultant nuclei here repre- 

 sented are all different from one another and have the sexual constitution (AB), 

 Zb)(Ab) Zd(aB) respectively ; but it is a matter of chance whether in any 

 P'icular basidium the^our nuclei belong to ariy one of ^^e jhree folowmg 

 / J R^ ir,h\ (Ah) laB)- ( 4.B) (AB), (ab), (ab) ; and (Ab), (Ab), (aM), 

 fa^r (Cf Pfi' 44.V No: 5 the itsTdil-body hks developed four sterigmata 

 and fou/'baldiospores, and the four haploid nuclei have crept through the 

 narrow necks of the sterigmata into the spores. Thus each spore is a haploid 

 Si and!tn the instance represented, the four spores have the sexual constitution 

 (AB), (ab), (Ab), and (aB) respectively. Highly magnified. 



young basidium the two nuclei of opposite sex unite, and the 

 fusion nucleus so produced soon undergoes two successive divisions 

 accompanied by a reduction in the number of chromosomes to 

 one-half and the segregation of sex and other factors (Fig. 143, 

 Nos. 2-4). Four sterigmata and four spores now develop on each 



