LIXNEAX SOCIETY OF LONDON. 5 1 



Evidence is broup;ht forward in this cominanicatioii to show 

 (i) that WiddriiKjtonia and CaUitris do not conform to the 

 " Cupressineae " type ; (ii) that Widdringtonia cannot be merged in 

 the genus ddlitris, but must rank as a distinct genus. 



(i) The chief points in which these two genera differ from the 

 Cu|)ressinece are as follows : — 



(a) The position of the Archegonia. In Cupressineae these 

 are found at the apex of the prothallus, in Widdringtonia 

 and CaUitris never at the apex. 

 (h) The multinucleate prothallus cells. 



(c) The development of the proembryo. Eight free nuclei 

 are not formed in these genera and the proembryo fills 

 the archegonium. 

 ('/) At least, three embryos may be formed from a single 

 proembryo. 

 Callitrine.e is suggested as a tribal name to include these two 

 genera (possibly also Actinostrobus and Tetraclinis). 



(ii) Both morphological and anatomical differences are pointed 

 out between CaUitris and Widdringtonia, which seem more than 

 sufficient to warrant the retention of Widdringtonia as a separate 

 genus. 



Of the morphological differences the more important of those 

 brought forward for the first time are : — 



{a) In Widdringtonia about 64 potential megaspore mother- 

 cells are formed at the base of the nucellus. In CaUitris 

 about two such cells are found, half way up the nucellus. 

 (6) The number and arrangement of the Archegonia differ 



materially in the two genera. 

 (<?) The microsporophyll normally bears 4 sporangia in Wid- 

 dringtonia, 3 in CaUitris. 

 Of the anatomical differences the most important is the occur- 

 I'ence of thickenings of the cell-wall in connection with the 

 bordered pits in both the wood and the transfusion tracheids of 

 CaUitris ; these are not found in Widdringtonia. 



A discussion followed in which Prof. Farmer, Dr. Stapf, and 

 the President engaged. 



Mr. George Maseee, F.L.S., followed with a lantern demon- 

 stration of his researches entitled : — 



Eyoltjtion op Parasitism in Fungi. 



To understand clearly the evolution of parasitism it is important 

 to grasp a fundamental point in the evolution of fungi generally. 

 The most primitive forms were aquatic, and reproduced by zoo- 

 spores which necessitated the presence of water to secure their 

 dispersion. As the fungi gradually took possession of dry land, 

 a second asexual or conidia form of reproduction, suitable for dis- 

 persion by wind, &c., was gradually evolved. This supplementary 

 conidial condition is always the form that has assumed a parasitic 



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