438 SYDNEY H. VINES. 



in whicli they lie. This point is called attention to in my 

 * I\Jonogra[)h on Elasmobranch Fishes/ page 39, where it is stated 

 that " the network in favorable cases may be observed to be in 

 connection with the nuclei just described. Its meshes are finer 

 in the vicinity of the nuclei, and the fibres in some cases aj)pear 

 almost to start from them." The nuclei in the yolk are knobbed 

 bodies divided by a sponge work of septa into a number of areas 

 each with a nucleolar body. 



Tlie Reproduction of Lichens and the Sexuality of the 

 AscoMYCETES. By Sydney H. Vines. M.A., Christ's 

 College, Cambridge. With Plate XX. 



In a previous number of this Journal^ an account was 

 given of the present state of the " lichen-gonidia question,*' 

 in which especial reference was made to the researches of 

 Stahl into the significance of the gonidia occurring ia the 

 hymeniuni of various lichens. Those researches, it was 

 pointed out, afforded strong evidence in favour of Schwen- 

 (lener's theory of the nature of lichens. Stahl's further re- 

 searches," of which ■a.\)x\q{ rt'sume, will here he given, into the 

 l)rocesses of their reproduction, seem to place the soundness 

 of this theory beyond reasonable doubt. 



No less than four distinct organs have been discovered at 

 various times in the thallus of lichens, all of which have 

 been regarded as being connected with their reproduction, 

 viz. (1) Soredia. (2) Spermogonia, bearing Spermatia, (3) 

 Apotliecia, containing asci in which spores are formed, (4) 

 Pycnidia, giving rise to Stylospores. 



The Soredia were first mentioned by Acharius,*'' their 

 structure was accurately described by Tulasne,* and their 

 development was fully made out by Schwendener.'' Their 

 significance appears to have been also completely understood 

 by Wallroth and Meyer. A soredium consists of one or more 

 gonidia surrounded by a mass of hyphoe, and when it is 



» April, 1S7S. 



* ' Uel). die Gesclilechtiiche Fortpflanzung der Collemaceen,' 1877. 

 ' ' Licheiingraj)hia Universalis,' ISIO. 

 ■• L. H. Tiiiasnc, ' Mem. s-itr les Lichens,' 1852, p. 24. 

 ^ lu Niigeli's ' Beitr. zur Wiss. B )t ,' Ilelt. ii, ISGO ; also, 'Flora,' 

 18G3. 



