1 87 1.] Light 113 



is generally preferred in dressing : should this prove to be the case any adultera- 

 tion of flax lint would be an undoubted evil, but lint wholly of cotton is used 

 extensively in hospitals, and had it been productive of any bad consequences 

 its use would soon have been discontinued. The peculiar lint known as 

 charpie used in continental hospitals and the marine lint were also noticed. 

 Microscopical examination fails to throw any light upon the alleged irritating 

 properties of cotton, as, although, the fibres are fiat, they have a perceptible 

 thickness at the edges, and are, moreover, rounded ; the section of a cotton 

 filament being somewhat like that of a thin tube flattened. It was suggested 

 that the cause of irritation was not owing to the form of the fibre, but to its 

 hygroscopic power of twisting when moistened and causing irritation by its 

 movement. 



Mr. J. W. Stephenson describes a new Erecting Binocular Microscope, which 

 he has had constructed for the purpose of carrying on dissections under 

 moderate powers. The pencils transmitted by the objed-glass are equally 

 divided and reflected by a pair of prisms, and again reflected by another 

 prism into the two bodies, which are placed at a very convenient angle for 

 dissecting operations; the image is, as the name indicates, non-inverted, and 

 the two fields equally illuminated. For ordinary observations the Wenham 

 binocular will be found preferable, not only on account of one-half of the pencil 

 being transmitted without reflection, but also from the facility with which it 

 may be converted into a monocular instrument. But for the especial set of 

 purposes for which it is designed nothing has yet equalled Mr. Stephenson's 

 instrument, either for comfort or convenience ; the definition is also remarkably 

 good when it is used with the low powers for which it is intended. 



In the " Transactions of the Devonshire Association for the Advancement of 

 Science," Mr. E. Parfitt describes and figures twenty-seven sponge spicules from 

 the greensand of Haldon and Blackdown, near Exeter. The specimens, which 

 were obtained by Mr. Vicary, are in remarkably perfect condition, being 

 imbedded in a very friable rock, from which they separated with the greatest 

 ease. Many of the spicules are identical with those of recent species of 

 sponges, described by Dr. Bowerbank, " British Spongiadas." One, Fig. 13, 

 closely resembles the spicules of Euplectella aspergillum (Venus's flower- 

 basket). Another, No. 26, is much like the spicules of Pheronetna (Holtenia), 

 dredged by Dr. Carpenter, in the " Lightning " and " Porcupine " expeditions. 



Spontaneous generation still furnishes matter for discussion ; it is a good 

 subject for controversy, and from the nature of the evidence procurable, is not 

 likely to be satisfactorily settled one way or the other. Mr. B. T. Lowne states 

 that he has boiled spores of penicilliwn in sealed tubes, in a solution of acetate 

 of alumina, and that within twenty-four hours many of them had germinated. 

 This goes very far to prove that some germs cannot easily be killed. If such 

 is the case with spores known to exist, how many included germs that have 

 escaped observation may retain their vitality, in spite of the severe treatment 

 to which they have been subjected. 



The subject of high power definition, especially with regard to the nature of 

 the markings on the scales of Thysanuridce (Podurce) and other insects, is now 

 being actively discussed, and will probably give rise to as long a controversy as 

 that on the DiatomacecB. Mr. J. Beck believes, from the manner in which fluids 

 diffuse themselves on the scale, that one of the surfaces (the outer when 

 in situ) is smooth, the other, the inner one, corrugated, or strengthened by 

 longitudinal ribs running from the base to the apex of the scale (" Monthly 

 Micro. Journal," Nov. 1870). Mr. S. J. Mclntyre has examined not only the 

 scales of most of the ThysanuridcB, but also those of several butterflies and 

 other insects ; the result is very fully described in his paper (" Monthly Micro. 

 Journal," Jan.). Mr. Slack, from evidence derived from torn and damaged 

 scales, considers that the beaded markings shown by high powers under 

 certain arrangements of the illumination are realities, the tear never passing 

 through but between the beads. Dr. Piggott discusses the subject from an 

 optical point of view, and calls attention to the means by which false images 

 are produced ; he has carefully studied the shadows formed when light is 



VOL. VIII. (O.S.)— VOL. I. (N.S.) Q 



