ON TIIE NUTRITION OF DROSERA ROTUNDIFOLIA. 17 



On damp surfaces in cabin, 82° 27' N, lat. Sporidia globose, 

 '00032 inch in diameter. In the British plant '0005 ; but in other 

 respects the two are identical. " This fungus grew abundantly on 

 damp surfaces in the cabin next to the berth-deck of the ' Alert * 

 during the winter of 1875-76. The atmosphere during the 

 winter was replete with sporules. Some of them must have en- 

 tered the ship." Some species of Mucor seem also occasionally 

 to have accompanied the Ckatomium. 



22. Venturia Myrtilli, Cooke, Jburn. of Bot. Aug. 1866, 

 tab. 50. fig. 4. 



On semiputrid leaves, Discovery Bay (J. C. Hart). Probably 

 the same thing occurred at Pnoven on Cassiopeia tetragona. 



28. Sphjsrella likeolata, De Not. — Sphseria lineolata, Desm. 

 PL Crypt, no. 1263 ; Cooke, I. c. tab. 51. fig. 31. 



On grass with the last. The perithecia are scattered ; but the 

 leaf is very small. Sporidia at first hyaline, uniseptate, gradually 

 acquiring a brown tinge, at length triseptate, the articulations 

 slightly constricted, *0013 inch long. 



24. DOTHIDEA BULLULATA, B. 



Discis parvis bullulatis ostiolis punctiforinibus notatis, e basi filamentosa 

 oriundis ; sporidiis uniseptatis uniserialibus utrinque leviter attenua- 

 tis. 



On leaves, Disco (H. C. Hart). Sporidia '0006 inch long, about 

 half as much wide. 



Experiments on the Nutrition/of Drosera rotundifolia. 



By Francis Dab^n, M.B., F.L.S. 



[Read January 17, 1878.] 



The mass of observation and experiment contained in my father's 

 book on Insectivorous Plants is all brought to bear on the cen- 

 tral theory of the book — the belief that the power of catching 

 and digesting insects is advantageous to the plants, and plays an 

 important part in their economy. If this explanation of the facts 

 be not accepted, we find ourselves in the presence of a number 

 of elaborate, but quite meaningless, structures and properties : 

 structures such as the trap of a Dioncea or Utricularia ; delicate 

 powers of discriminating between different kinds of stimuli, as in 

 Drosera ; and properties of forming a peptic secretion, such as that 



LTXN. JOURN. BOTANY, VOL. XTII. C 



