LINNEAN SOCIE'ir OF LONDOX. 7 



in various parts of this country. Tlie tuber is the part most 

 frequently attacked, but very young leaves are sometimes infected. 

 In tubers the young " sprouts " are attacked, and owing to the 

 stimulation induced by the parasite in infected spi'outs rapidly 

 increase in size aud form large coralloid masses or warts, which 

 frequently cover the greater portion of the surface of the tuber. 

 These masses eventually become blackish-brown in colour, due to 

 the presence of myriads of dark-coloured resting-spores. 



Infection always takes place from without, consequently the 

 epidermal or peripheral cells alone are infected. The presence of 

 mature resting-spores imbedded deeply in the tissue of the host, 

 at first sight appears to contradict this statement, but this appear- 

 ance is due to the rapid growth and division of uninfected 

 epidermal cells, which soon form a tissue superposed on what 

 was previously the peripher}^ . 



A point of interest in connection with this disease is the absence 

 of periderm, which in other diseases of potato tubers is so readily 

 formed. On germination, the inner, thin hyaline wall is extruded 

 in the form of a sphere, through a crack in the thick coloured 

 outer wall of the resting-spore. The thin wall of the extruded 

 inner membrane soon deliquesces, aud liberates myriads of ellip- 

 tical, uniciliate zoospores. 



The facts that the host is infected through the epidermal or 

 peripheral cells, and the extrusion of the inner wall of the resting- 

 spore as a sphere, from which the zoospores escape in an active 

 condition, indicate that the parasite belongs to the old and well- 

 known genus Syncliytrium. 



What happens to the zoospores after their liberation into the 

 ground remains to be discovered, but experiments conducted at 

 Kew prove that soil once infected produced a diseased crop even 

 after a period of five years. 



Prof. Dendy, Mr. A. P. Young, and the President contributed 

 some remarks, and Mr. Massee replied to certain questions. 



Messrs. H. & J. Groves, P.L.S,, exhibited specimens of Luzula 

 pallescens, Besser, collected in Woodwalton Fen, Hants, by Mr. J. 

 Groves in company with Mr. E. W. Hunuybuu, who discovered 

 the plant there last year. L. ]jallescens has previously heen 

 recorded as British from specimens collected by the Rev. Augustin 

 Ley in 1898 at Presteign, Radnorshire ; but on examination of 

 Mr. Ley's specimens, they proved to be merely a pale state of 

 L. erecta. In Messrs. Groves' opinion the differences between 

 L. pallescens and L. erecta were sufficient to warrant their being 

 regarded as distinct species ; the principal characteristics of 

 L, pallescens being the very numerous smaller oval heads, the 

 much smaller perianths and fruits, and the minute seeds, besides 

 which there was a great difference between the outer and inner 

 perianth-segments. Though originally described from Scandi- 

 navia by Wahlenberg (under the genus Juncus), the headquarters 



