284 



SCIENCE-GOSSIP. 



Variations of the Leaf-Blade. — This subject 

 is extremely important in many respects ; but for 

 that very reason we must be all the more careful 

 and cautious in assigning true causes to the effects 

 that we see produced in nature. For instance, I 

 cannot agree with the conclusion (ante p. 210) 

 that warmth and moisture favour the growth of the 

 parenchymatous and vascular tissues of land 

 plants. It is indeed the first time that I ever read 

 that midsummer was characterised by warmth and 

 moisture. The principal factor in the production 

 of leaf variation is an intense illumination which, 

 all other conditions being alike, evokes the following 

 differences in structure, viz. : the palisade paren- 

 chyma exhibits a greater development ; the leaf is 

 thicker, has a greater abundance of chlorophyll, 

 the different elements of the epidermis are more 

 developed, the cuticle in particular is much thicker, 

 the stomata are more numerous, especially on the 

 upper surface. Light, however, is not the sole 

 cause, it is aided purely and simply by dryness of 

 the air, and this produces precisely similar effects, 

 although in a much less marked degree. The third 

 and last agency in the work is that of temperature, 

 and this, when warm, aids the two foregoing 

 causes, but when cold it helps to develop the 

 protective tissues and at the same time diminishes 

 the number and size of the vessels, and also the 

 tissues whose function it is to nourish the plant. 

 These facts taken together and wrought out on the 

 basis of the Lamarckian philosophy will be found 

 to harmonise exceedingly well with the physio- 

 logical needs of the plant under the physical 

 conditions specified above. To come to details, 

 the cases of the leaves of the fig-tree figured at 

 page 210 (attte) must now be considered. In this 

 instance the leaves do not "become larger as the 

 warm weather advances"; it is not the warmth 

 and dampness of midsummer that favours the 

 rapid lengthening of the midrib ; both efiects are 

 really due to the increased illumination and 

 dryness incident to that season. The rapid 

 lengthening of the midrib is not a cause, it is an 

 effect due to the same causes that produce a 

 broader or narrower and thicker leaf. Mr. Griset's 

 explanation of the sub-division of the leaves of the 

 bittersweet and of aquatic plants is correct, 

 except that want of light is only a circumstance 

 and not an active agent. The round entire form of 

 many floating leaves are not floats to buoy the 

 plant to the surface of the water. It is the inner 

 or organic needs of the plant under the conditions 

 of its environment which prompts the "highly 

 accommodating protoplasm " to adapt itself to 

 circumstances, and thuswise there is formed on 

 the surface of the water a broadly and beautifully 

 rotund area of leaf structure which, although fully 

 and freely exposed to light and air, does not need 

 any contraction of its contour or any extra thick- 

 ening of its tissues (as in land plants) in order to 

 preserve it from the deadly effects of a too 

 excessive transpiration. — [Dr.] P. Q. Keegan, Lon- 

 don; February /^th, 1897. 



Nesting-place of the Wedged-tailed Gull. 

 — In "Science," January 29th, there is an interesting 

 article on the discovery, by Dr. Nansen, of the 

 breeding-grounds of Ross' gull, also known as the 

 wedge-tailed or rosy gull, Rhodostethia rosea. In a 

 letter published in the "Daily Chronicle," Dr. 

 Nansen states that he found flocks of rosy gulls on 

 August 6th, in latitude ST^ 38', east longitude 63°. 

 The birds were seen near four small islands, called 

 "Hirtenland" by Nansen, a little north-east of 

 Franz-Josef Land. Though Nansen did not 

 actually find nests he found the birds abundant, 

 and concluded that their nests were probably 

 near by. 



Pallas' Willow Warbler in Norfolk. — Mr. 

 Thomas Southwell, in the " Zoologist," gives a 

 detailed account of the finding of a specimen of 

 this rare v/arbler, Phylloscopus proregulus, at Cley- 

 next-the-sea, Norfolk. Mr. Ramm, the person 

 who shot the bird, says that he found it amongst 

 the long grass on the bank or sea-wall not far from 

 the sea at Cley, a locality which has produced 

 many rare migrants. Apparently the last appear- 

 ance of Pallas' willow warbler in Europe was 

 that mentioned by Herr Gatke, in his " Birds of 

 Heligoland," p. 293. It was found by Glaus 

 Aeuckeus, one of his collectors. Mr. Seebohm, in 

 the " Catalogue of Birds in the British Museum " 

 (vol. v., p. 72), states that this bird breeds in the 

 sub-Alpine districts of South-Eastern Siberia, and 

 throughout the Alpine districts of the Himalayas 

 from Cashmere to Burma, passes through North 

 China on migration, and winters in South China, 

 Burma and Bengal, and, it may be added, occa- 

 sionally strays as far west as Heligoland and the 

 east coast of Britain. 



The Zoological Society has just acquired a 

 female monkey of the genus Cercopithecus, which is 

 of very great interest, inasmuch as no specimen of 

 this particular species has been received at the 

 menagerie since 1841. Dr. Sclater put this species 

 (C. tantalus) among those which he had not seen 

 when he made his list of the known species of this 

 large genus. In 1841 Mr. W. Ogilby called the 

 attention of the members of the Society to a new 

 species of monkey then in the Gardens, to which 

 he gave the specific name tantalus. He referred to 

 the group now called "green monkeys," and 

 compared it with some of the members of that 

 group. No details were obtainable as to the 

 previous origin of that specimen. The question as 

 to its native land, however, is now definitely 

 settled, for the new arrival is known to have come 

 from West Africa. She presents many points of 

 resemblance to the Grivet (C. griseo-viridis), from 

 East Africa and Abyssinia ; to, the ordinary green 

 monkey (C. callitriclnis), from West Africa ; and to 

 the vervet (C. lalandi), irom South Africa; yet the 

 points of difference are sufficiently well marked to 

 show that she can be classed with none of the 

 three. 



