118 



KNOWLEDGE. 



[Mat 1, 1899. 



Fireball uf April 4th.— On April 4th, at 7h. 59m., Mr. C. 

 Parker, of Handsworth, Birmingham, saw a brilliant meteor. It 

 started from ij Ursae Majoris, and finished its coarse one degree 

 beyond /3 Cassiopeise. When near the latter star, it broke up into 

 three pieces. The meteor was brighter than Jupiter, and ex- 

 hibited a marked variation in colour during its flight. The same 

 object was observed by the Rev. E. Killip, of St. Anne's on-Sea, 

 Lancaster, and he gives some details in The Ent/l'^h Mechanic 

 (April 14th). The time was 7h. 56-.jm., and the meteor was 

 estimated as fully twice as bright as Venus. It was first 

 observed near a Cassiopeise, and travelled leisurely towards 4> 

 Andromedse, dying out when eight or ten degrees from the 

 W.N.W. horizon. This fireball appears to have been directed 

 from a well-known April radiant of large meteors at about 

 2l).i--ll= in Libra : but the above two observations appear to be 

 somewhat discordant, and a satisfactoiy real path of the object 

 ■ cannot be computed from them. 



Fireball Epochs. — There are many well-known fireball 

 epochs during the year, and it is intended to make special obser- 

 vations with a view to discover the principal showers to wliich 

 they belong. It is certain that at some of these periods a large 

 number of streams are dis])la3'ed, and that the jjaths of such fire- 

 balls as have been observed will not conform with any one 

 radiant. They have exhibited considerable variety in their 

 directions of flight, but it is hoped that further observation will 

 reveal many of the chief systems of fireballs. 



ilttcvosfopp. 



By John H. Cooke, f.l.s., f.g.s. 



The respiratory system, and other organs of many insects, may 

 be clearly shown by bleaching with peroxide of hydrogen. 



A saturated solution of neutral red in (>8 per cent, sodium 

 chloride is recommended for demonstrating the hsemoglobige- 

 nous granules in the erythrocytes of certain animals, such as 

 the lamprey, frog, guinea-pig, and fowl embryos. 



A solution consisting of pure glycerine and three per cent, 

 formalin, in the proportion of three parts of the former to two 

 parts of the latter, has been suggested as an effective preserva- 

 tive for fresh-water sponges. Unlike alcohol, it does not 

 decolourize the specimens. 



One of the principal difficulties hitherto ex]ierienced in the 

 use of the electric arc lamp for microscopical purposes has been 

 that of keeping the position of the arc constant and of securing 

 a sufficiently sm;ill and uniform source of light. At a recent 

 meeting of "the Quekett Club, Mr. J.E. Barnard gave an account 

 of the improvements he had made in this direction, whereby he 

 had adapted an electric are lamp for micrographic and photo- 

 micrographic purposes. He regulates both the position of the 

 carbons and the distance between the carbon points by hand in 

 such a way, that, by reference to cross wires on a glass screen, 

 the source' of light can always be kept in the same place, while 

 " the oblique jwsition in which the carbons were set enabled the 

 small point of intense light from the incandescent crater of the 

 positive carbon to be used as a source of unvarj-ing and steady 

 illumination of small area but very great intensity.'' This 

 steadiness and intensity render the light specially suit;ible for 

 photographing with high power objectives. 



The last issue of the Transactions of the South-Eaxtern iniun 

 of Scientific Societies, contains inter alia a suggestive paper by 

 Mr. E. M. Holmes, f.l.s., entitled "Botanical Work wanting 

 Workers." The author refers briefly to work that may be done 

 among the mosses, scale mosses, fungi, lichens, marine algae and 

 freshwater algaa, and indicates lines of work that might be 

 followed and the localities in south-eastern England where the 

 best results are likely to be obtained. He appeals specially to 

 microscopists to take U]i the life-history of algae, both fresh- 

 water and marine, but particularly the latter. Little is known 

 of the changes that take place between the times when these 

 plants disappear and reappear again ; and it is not even known 

 whether some of the algae are not merely stages of growth of 

 others. This is especially true of those plants in which only 

 vegetative growth and reproduction are known, and in which 

 sexual reproduction is unknown. It is suggested that the 

 systematic observation during cultivation of such plants as 



Porph3Tidium, Chroococcus, OscUlaria, Tetraspora, and Schiro- 

 gonium, might add considerably to our knowledge of their ILfe- 

 histories. 



Students of marine algae are likewise appealed to. We know 

 very little of the life-cycles of the common Laminarise. Mr. 

 Holmes therefore suggests a careful study of these by cultivation 

 from their spores. A microscopical examination once a fort- 

 night throughout the year might result in finding the cystocarps 

 of Rhndymenia palmata, the unknown tetraspores of some of 

 the species oi Phi/Unphora, Ahnfeltia 2iUt:(it(i, auA of Gigartina 

 niamillosa, as well as the fructification of Sphacelaria scopnria, 

 which, so far as is known, has never been found in this country. 

 The paper is as practical as it is suggestive, and it is well worth 

 the consideration of those who are desirous of taking up a line 

 of research. 



The following useful piece of apparatus for carrying material 

 through the processes of fixing and hardening has been devised 

 by Mr. W. C. Stevens, of Kansas University. It is specially 

 suitable for very small objects, such as root-tips, sporanges and 

 young flower buds. Small glass buckets are made by cutting up 

 glass tubing one centimetre in diameter into lengths of three 

 centimetres. By means of heat, one end of each piece is turned 

 out so as to form a rim ; over this a piece of muslin is tied. 

 The little bucket is provided with a suspender by means of a 

 piece of thread fixed in the middle of the bottom ; and the 

 specimen is then placed in the bucket and suspended in the 

 fixative fluid. 



To obtain the most satisfactory definition with high power 

 objectives, "critical '' illumination is a sine qiui non. The micro- 

 scope should be placed in a horizontal position, with its mirror 

 turned on one side, and the lamp and microscope should be so 

 arranged that the thin edge of the flame shall be projected along 

 the o])tical axis of the condenser, and so that its image, when 

 viewed with a one-inch objective shall be sharply defined in 

 the same field of view as that occupied by the objects when 

 under observation. The substitution of the one inch objective 

 for either a f^th, j^th, or a jgth, may now be made, and, after 

 a slight readjustment of the achromatic condenser, it wiU be 

 found that, the field of view will be so brilliantly illuminated, 

 the most minute flagellate organisms are defined with an amount 

 of sharpness rarely obtained under any other conditions. 



Of late years considerable progress has been made in the 

 methods adopted for the determination of the structural 

 characteristics of steel by means of the microscope. In a paper, 

 read before the American Microscopical Society, Mr. F. S. Rice 

 briefly reviews the present state of our knowledge of the subject, 

 and gives some verj' interesting details regarding the preparation 

 and mode of examination of specimens. His experience has 

 shown that specimens three-fourths of an inch in diameter, aud 

 mounted on ordinary slips, are the most convenient. He depre- 

 cates the use of emery and crocus papers, rouges, and wheels 

 charged with polishing and cutting compounds, but suggests 

 instead, that the best sections are obtained by carefully grinding 

 off the surface to a plane, by hand, on an ordinary quick-cutting 

 oil-stone, then on the finest Belgian oU-hone, and, finally, 

 polishing on a piece of chamois leather tightly stretched over a 

 block of wood charged with peroxide of tin. The specimen is 

 finished by washing thoroughly with alcohol, followed by a little 

 chloroform. 



Professor E. Mead Wilcox, of Harvard University, advocates 

 in the columns of the Jmirnal oT Applied Microscopy the use 

 of soap for imbedding plant tissues. It is frequently found 

 that it is not practicable to apply either the parafl5n or the 

 collodion methods on account of the time that they require. 

 Fleming, Lee, and Pfitzer have each suggested the soap method, 

 and have practised it at different times with more or less success. 

 Prof. Wilcox now gives his experiences in this direction. He 

 finds that glycerine and alcohol together as the solvent give the 

 best results. A tablet of Pear's soap was cut into small pieces 

 and dissolved in a mi.xture of equal parts of niuety-five per cent, 

 alcohol and glycerine. The resulting liquid was then poured 

 into a warm, shallow dish and allowed to harden, after which it 

 was ready for use. Before imbedding the tissues it has been 

 found desirable to immerse them in a diluted solution of the 

 soap, in order that thorough penetration or infiltration may be 

 secui'ed. Final imbedding may then be accomplished in a watch 

 glass. 



