308 Mr Bateson, Notes on Hybrid Cineramas. [May 10, 



vidalii, Pointsettia. I imagine that the laticiferous vessels supply, 

 as it were, an efficient system of drainage by which a large 

 quantity of fluid can at once escape, and therefore quickly alter 

 the internal pressure in the tissues. 



My work also bears on the question of mechanism in another 

 way. It has been assumed, I believe, incorrectly, that light opens 

 the stomata because the assimilation of the guard cells leads to 

 osmotic material being built up ; the closure in darkness being 

 due to loss of such osmotic matter. 



Schellenberg* has sought to uphold this view by placing 

 leaves in air free from C0 2 , where he finds that the stomata 

 are shut. In none of my experiments did I see any signs of 

 closure being due to absence of C0 2 . 



But in any case, another of my results is unfavourable to 

 this view. Many plants reopen their stomata if they are kept 

 continuously in the dark for several days. Whatever is the 

 explanation of this fact it is clearly not due to returgescence of 

 the guard cells owing to assimilation. This fact was first observed 

 by my assistant, Mr Elborn, to whom I am indebted for much 

 valuable help. 



(2) Notes on hybrid Cinerarias produced by Mr Lynch and 

 Miss Pertz. By W. Bateson, M.A., St John's College. 



It is stated by many writers that the garden Cineraria arose 

 as the hybrid offspring of several species of Senecio from the 

 Canary Islands. This statement has been questioned by Mr 

 Thiselton Dyer on various grounds. The author exhibited 

 hybrids raised from S. cruentus, S. multiflorus and 8. Heritieri 

 (= lanatus) raised in the Cambridge Botanic Gardens by Mr Lynch 

 and Miss Pertz which illustrated the great variability which 

 appears in the offspring of the various crosses. In particular, 

 specimens of Heritieri % x cruentus </ and of the reciprocal cross 

 were produced, showing excessive variability and proving how 

 greatly the peculiar characters of Heritieri may be obscured in 

 the offspring, even of the first cross. Five specimens of midtiflorus 

 $ x Heritieri g were exhibited, each of which was quite distinct 

 from the rest. Experiments had entirely confirmed Darwin's 

 observation that Cinerarias are self-sterile in a high degree. 

 They hybridize on the contrary with great readiness. An acci- 

 dental hybrid between Heritieri % x garden Cineraria £ and the 

 reciprocal were also shown, the two plants being quite unlike 

 each other, the former being an upright plant of a rather woody 

 habit, resembling poor specimens of the garden Cineraria, while 



* Bot. Zeitung, 1896. 



