210 THE JOURNAL OP BOTANY 



under the influence of Dr. Hook, then Vicar of Leeds, and joined 

 the Church of England. He married in London, May 2Gth, 1852, 

 Miss JuHa Durieu, who died at Barnstaple, December 15th, 1906, 

 in the 79th year of her age ; by her he had four sons and five 

 daughters, of wliom one son and four daughters survive. 



W. P. HiERN. 



SHOBT NOTES. 



SempervivujI arachnoideum. — I have been watching for 

 several months a small pot of the Spider's-web House-leek on a 

 sheltered window-sill which gets practically no rain, but plenty 

 of sun. When it rained heavily and the air was saturated with 

 moisture the rosettes, amply furnished with a white network of 

 long hairs, shrank in size — one decreased from 30 mm. to 

 20 mm. in diameter ; but soon after the sun appeared the leaves 

 expanded again. It is generally supposed that the leaves of the 

 rosettes point directly upwards and are bound together by the 

 " cobwebs " to allow the sunlight to fall obliquely on their 

 surfaces ; or, in other words, that this is an adaptation tending 

 to reduce the loss of water given off by the leaves. So this 

 behaviour of S. arachnoideum in captivity is interesting. When 

 the plant grows in quite shady places, the network is usually 

 much less pronounced, and instead of being white the rosettes 

 are green. This again supports the view that the cobweb hairs 

 are developed to lessen the danger from evaporation. Fraulein 

 Dintel of Vienna has shown that the cobwebs of this plant are 

 moditied glandular or secretory hairs, and that it is their secretion 

 which forms the means by which they are bound together into 

 a web. There is an excellent photograph of the rosettes of 

 S. arachnoideum, and two showing " the migration " of S. mon- 

 tanum, in Dr. Newell Arber's most useful book. Plant Life in 

 Aljmie Sivitzerland. — H. S. Thompson. 



Sedum dasyphyllum. — On May 16th I gathered on a wall near 

 Portishead two pieces in small bud, and left them, without roots 

 and with no water, on a table in a room facing S.E. In about 

 three weeks the top bud of each had expanded and showed the 

 stamens ; and to-day (June 13th) they are as fresh as when 

 gathered. Mr. J. W. White {Fl. Bristol, 323) quotes the late David 

 Fry as saying that this plant "survives sometimes in a sur- 

 prising way when a wall is repaired or repointed, coming out 

 again apparently through the hard mortar." — H. S. Thompson. 



Caterpillars and Oaks. — With reference to what has ap- 

 peared in the public press relative to the devastation caused by 

 caterpillars to the oak trees at Ashtead, you may be interested to 

 know that some three or four years since a similar occurrence 

 took place in the oak plantations in Richmond Park. The denu- 

 dation of the trees was so severe that in the spring of 1913 

 H.M. Office of Works consulted Mr. Maxwell Lefroy, the ento- 

 mologist of the Royal College of Science, with a view to stamping 



