4/6 



NA TURE 



[March ig, 190^ 



The Yorkshire Naturalists' Union is fortunate in enlist- 

 ing the services of specialists to assist in the compilation 

 of county records, both botanical and zoological. Several 

 series representing different branches of natural history have 

 been, and are being, published in its Transactions. One 

 part, lately issued, completes the county list of fresh-water 

 alga;, which has appeared in four instalments, and for which 

 Mr. W. West and Mr. G. S. West are responsible. Another 

 volume, which is produced under the joint authority of Mr. 

 G. Massee and Mr. C. Crossland, constitutes the first in- 

 stalment of the " Fungus Flora of Yorkshire," and enumer- 

 ates the Gasteromycetes and Agaricinea;. Although only a 

 small portion of the county has been thoroughly explored, 

 the list will summarise the results obtained during several 

 successive annual forays, and will also include the records 

 noted by independent collectors. 



At the meeting of the American Association held in Wash- 

 ington last December, Prof. Douglas Campbell selected as 

 the subject of his address. " The Origin of Terrestrial 

 'Plants." The subject is one to which the writer has con- 

 tributed many valuable suggestions and arguments, but on 

 the present occasion no new ideas are presented. It may 

 be noted that although Prof. Campbell alluded to the possi- 

 bility of the leaf arising by mutation as a sudden outgrowth 

 on the sporophyte, he looks upon the apophysis of the moss 

 capsule as an early form of such emergence. Witli regard 

 to the origin of the root, the view is expressed that this 

 arises as a modification of the foot. 



A list of fresh-water algae, collected in Java by Dr. 

 Raciborski, and named by Mr. M. R. Gutwiiiski, appears 

 in the Bulletin International de I'Academie des Silences de 

 Cracovie. Sixteen new species are recorded under the 

 genera Closterium, Penium, Xanthidium, Cosmarium, 

 Staurastrum and Spirulina. 



A small brochure, published by the University College 

 of Wales Scientific Society, furnishes a list of flowering 

 plants and ferns which have been found in the neighbour- 

 hood of Aberystwyth. The compilation of such records is 

 to be strongly commended, since it furnishes a definite ob- 

 jective, and is therefore certain to provide an extra stimulus 

 for the excursions of local societies. The list now produced 

 may, with advantage, be amplified by inserting notes on 

 habitats, dates and descriptions of peculiar forms. 



The first specimen-part of the " Prodromus Flora; Britan- 

 nicae " was issued by the author, Mr. F. N. Williams, in 

 June, 1901, and since that date two more numbers have 

 been published, the last bearing the date November, 1902. 

 The orders Cucurbitaceae, Lobeliacea; and Campanulacese 

 appeared in the first portion, while the remainder of the 

 work, so far as it goes, is devoted to the Composite, under 

 the disguised name of the Asteraceaj, and the last part is 

 given up to and contains the whole of the genus Hieracium. 



The presidential address on the " Rise and Progress of 

 Ecology," delivered by Prof. V. M. Spalding before the 

 Society for Plant Morphology and Physiology at the Wash- 

 ington meeting, appears in Science. The writer indicates 

 two phases of the subject, the compilation of facts and the 

 subsequent incorporation of these into conclusions, and 

 refers to a recent paper, by Mr. Paul Jacquard, on alpine 

 plants. 



The Annual report of the Board of Agriculture and 1 >.-- 

 partment of Public Gardens in Jamaica, for the year 1901-2, 

 also an authorised Guide to Hope Gardens, have been re- 

 ceived. In the former certain changes in the disposition 

 of the staff are recorded, and also the approval of the legis- 

 lative council for the purchase of land on St. Jagos estate, 

 part of which may possibly be utilised for experimental 

 work. A survey is given of horticultural experiments and 

 educational work. The Guide includes a description of the 

 botanic gardens by Mr. W. Jekyll. 



In the current number of the Trinidad Botanical Bulletin 

 there appears an instructive article on the care of pastmvs. 

 It is pointed out that native grasses are likely to be more 

 successful than those grown from imported seed, or if im- 

 ported they may with advantage be introduced from 

 countries which possess a similar climate. For the destruc- 

 tion of parasol ants, carbon bisulphide, used with due pre- 

 caution, is recommended. In connection with this and 

 other uses, such as a seed fumigator, an article giving 

 American experience is reprinted. 



NO. I 742, VOL. 67] 



THE PREVENTION OF DEW DEPOSITS 

 ON LANTERN SLIDESA 

 T ANTERN slides are so commonly used in lecture illus- 

 trations that the following hints may prove to be 

 useful : — 



The deposit of dew which frequently takes place is very 

 annoying, but its cause is easily traced, and, 1 believe, can. 

 easily be removed. Dew means that the surface on which 

 it is deposited is colder than some other surface with which 

 the air must have previously been in contact, and at which, 

 it has become saturated with moisture ; hence the problem 

 consists in discovering that surface, and in preventing its 

 becoming hotter than the glass slide. 



There is a kind of tradition amongst makers of lanterns- 

 and their accessories that every surface should be black. 

 There is no reason at all for this practice, which is probably 

 in all cases the cause of the trouble I am dealing with. 

 My attention was called to the subject by a lantern used for 

 the projection of objects much larger than the ordinary 

 slides. When these were used, they were put in a wooden 

 frame which presented a large carefully blackened surface 

 to the condenser. The condenser always became quickly 

 covered with dew. On pasting a sheet of white paper over 

 the blackened wood of the frame which held the slides, the 

 trouble was at once removed. What had happened was that 

 the black wood became heated, and gave up a large amount 

 of moisture. When covered with a white reflecting surface, on 

 the other hand, the heating was sufficiently reduced to pre- 

 vent the distillation of moisture. The deposit of dew on the 

 condenser lenses may therefore easily be avoided. 



More troublesome is the dew which forms in the space 

 between the photographic picture and the glass cover of the 

 slide. I have not personally been troubled with this, and 

 therefore I have not had any experience as to how to get 

 rid of it, but I feel sure that a great deal could be done by 

 removing the blackened paper frame which is generally in- 

 serted between the two glasses, and replacing it by tin foil 

 or white paper. It is obvious that if we take care that 

 the glass of a slide forms the hottest surface in the neigh- 

 bourhood, no dew can be deposited on it. As the glass 

 absorbs a good deal of the more intense rays, and the slide 

 itself is appreciably warmed, there should be no trouble in- 

 securing that nothing else should get warmer. The only 

 possible cause which could not be dealt with would be the 

 evaporation of water from the silver deposits which form 

 the photographic picture, but there is no reason to suppose 

 that they condense a sufficient amount of moisture to do 

 much mischief if the slides are carefully dried to begin with. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Sir Michael Foster has resigned the chair of physiology 

 at Cambridge, which he has held since 1S83, when the 

 professorship was established. 



Prof. J. A. Ewing, F.R.S., professor of mechanism and 

 applied mechanics in the University of Cambridge, has 

 been appointed Director of Naval Education, under the new 

 scheme of training. The scheme was discussed in con- 

 nection with the Navy Estimates on Monday, and an amend- 

 ment disapproving of it was moved, but upon a division 

 the amendment was rejected. 



The Liverpool Marine Biology Committee has, in con- 

 sultation with the Nature-Study Association of Teachers of 

 Liverpool, issued a circular expressing its willingness to 

 make arrangements for a special class in elementary marine 

 biology, to illustrate the principles of nature-study, and to 

 be held at the Port Erin Biological Station during the 

 Easter holidays. The course will extend from April 10-17. 

 Intending students should communicate with Mr. F. J. Cole, 

 University College, Liverpool. 



At the annual meeting of the National Home-Reading 

 Union on March 13, Dr. Richard Garnett delivered an 

 address in which he dealt with the community of aim and 

 feeling between the Union and the public library system. 

 One great wish of the Union is through the systematic 



1 Read at the British Association Meeting in Belfast, September, 1902, by- 

 Prof. Arthur Schuster, F.R.S. 



