NOTES OX RECENT RESEARCH. 



233 



ascertain whether under a comparatively bright sky and warmer tem- 

 perature, as contrasted with the atmospheric surroundings of England, 

 circumnutations might be performed more rapidly than in the shortest 

 time limits given by Darwin. Tables devoted to each species record the 

 results, with comparisons of the periods recorded by Darwin. Universally 

 the time was much shorter. — IT. C. C. 



Oak Leaves and Climate. 



Climate and Leaf in the genus Quereus. By Wilh. Brenner 

 (Flora, vol. xc. 1902, pp. 114-160 ; 21 woodcuts). — The genus presents 

 leaves of several types : (1) entire, rounded elliptical, or lanceolate ; 

 (la) serrate or serrate pungent ; (2) filiform-lobate ; (3) sinuate-lobate. 

 Different types of texture occur, from papery to leathery, and of 

 anatomical structure : (1) with aquiferous cells occurring in the spongy 

 parenchyma ; (2) with great development of the spongy parenchyma ; 

 (3) with great development of the epiderm. Branched hairs frequently 

 occur on the underside. The stomates are always simple, and rarely 

 either sunk or prominent. The venation may be : (1) Camptodromal, 

 each rib tapering as it runs arching in towards the next ; (2) Craspedo- 

 dromal, nearly straight, running into a tooth or lobe; (3) Brochedo- 

 dromal, losing itself by branching before reaching the periphery. 



Experiments on seedlings of Q. sessilis, pedunculated, and Suber 

 raised in dry air, in moist air, and under alternating conditions showed 

 an increase of palisade tissue, a tougher, thicker leaf, more branching 

 ribs, and a more entire margin as the dryness increased. 



Comparison of leaves of given species show differences in form, venation, 

 and anatomy, as they grow in sun or in shade, and these are repeated in 

 specimens from different stations ; notably pungent serrate species tend 

 to become simply serrate, and simply serrate and entire leaves to become 

 lobed when transferred to more temperate stations. A detailed comparison 

 follows between the species represented in Grisebach's geographical 

 regions. The author infers that the results point clearly to the con- 

 clusion that the specific variations must be due to the hereditary trans- 

 mission of characters originally acquired in adaptation to the climatic 

 conditions of growth. — M. H. 



Oak Parasite. 



Conopholis americana, Observations on. By Lucy L. W. 

 Wilson, Ph.D. (Contr. Bot. Lab. Phil. vol. ii. No. 1, p. 3 ; 1898 ; 6 plates). 

 Showing that this plant, resembling Orobanche, is parasitic on the Oak, 

 and may form a fringe of growth round the trunk at a distance of ten or 

 more feet ; that it is perennial for at least eight or ten years, and first 

 affects young roots, usually starving the portion beyond the point of 

 infection ; that the union between parasite and host is a very intimate 

 one, the parasite being developed endogenously within its host, which 

 rises up and encloses it after its germination. Resembles Balanophora 

 and Bafflesia in this respect, rather than Orobanchcce, that the irritant 

 action of the parasite causes swelling up of the host root and great 

 multiplication of its sclerenchyma patches. 



