340 Mr Darwin, On Farmer's method, etc. [Nov. 8, 



than 2 or 3 hours of darkness, i.e. when the assimilative function 

 is not seriously inhibited. It should be possible to demonstrate a 

 second maximum in the blue 1 , but I am here considering the 

 question simply from the point of view of laboratory teaching, and 

 in this connection I think it best to confine the demonstration 

 to a comparison of red and green light. 



(2) Artificial Cultures of Stereum, a Timber-destroying 

 Fungus. By Prof. Marshall Ward. 



(3) On Encephalartos Ghellinckii, Lem., a rare Cycad. By 

 A. C. Seward, M.A., St John's College. 



The subject of this note is one of the less known species of the 

 African Cycadean genus Encephalartos. In 1895 2 1 called attention 

 to the unusual form of the fronds of Encephalartos Ghellinckii, 

 Lem., and figured a small piece of a leaf from a specimen in the 

 British Museum herbarium. A plant in the Royal Gardens, Kevv, 

 bearing a single frond, first attracted my attention to the species. 

 The large and stout fronds of such species as Encephalartos 

 horridus, Lehm., E. Gaffer, Miq., E. Lehmanni, Lehm., E. Alten- 

 steinii, Lehm., and others with broad and occasionally spinous 

 pinnae represent the type of plant which is usually regarded as 

 characteristic of the genus. Encephalartos cycadifolius 3 , Lehm. 

 (= E. Frederici-Guilielmi) forms a connecting link between species 

 with narrower pinnae and E. Ghellinckii. 



The first account of E. Ghellinckii was published by Lemaire 4 

 in 1867, the description being founded on a plant in the nurseries 

 of Verschaffelt, by whom the Cycad was obtained from the central 

 region of South Africa. The following is Lemaire's diagnosis of 

 the species : — 



" Caudex ut in praecedente {i.e. Encephalartos villosus, Lem.). 



Frondes 5 — 12 erectae et illae ut praecedentis dispositae, totae 

 gossypinae metrales et ultra (quas vidi solum in prima aetate 

 frondationis sese evolventes ; rhachi cylindrica serius siccata sub- 

 plana) foliolis approximatissime oppositis v. rarius alternis omnino 

 ob arctissimam marginum revolutionem lineari-filiformibus apice 

 mucrone robusto aculeiformi pungentissimo terminatis, marginibus 

 integris acus recte simulantibus. 



Coni ,-f et $ nobis hucusque ignoti." 



1 Using a screen of ammoniacal copper sulphate which lets through a good deal 

 of green as well as the blue end of the spectrum. 



2 " The Wealden Flora " ( Catalogue of the Mesozoic plants in the British Museum), 

 vol. ii. 1895, p. 22, PI. in. fig. 3. 



3 ibid. PI. in. fig. 6. 



4 Lemaire, C, " L'illustration horticole," Journal special des serres et des jar dins, 

 vol. xiv. 1867, p. 8Q. 





