246 



SCIENCE- GOSSIP. 



vessels is perceptible, and these may be traced 

 right through to pedicles of the tufts of bristles at 

 the wing's point, the function being, I believe, to 

 supply the scales with the liquid which, according 

 to Dr' Eoyston Pigott, is found between the upper 

 and lower membranes of the scales. I am writing 

 without the book, but think this is so There is 

 certainly, as can be clearly seen with a good 

 objective of wide angle, an intricate system of 

 capillaries feeding every pedicle in the membrane. 

 Antennae of Cockchafer (fig. 2). — Of all the remark- 

 able developments which insect antennae attain. I 

 think there are not anymore peculiar and interest- 

 ing than those of the organs of the cockchafer, 

 with their leaf -like expansions, folding out upon one 

 another like the sticks of a fan. This slide contains 

 two of these lamellae mounted in balsam. The ac- 

 companying sketches are intended to show the pecu- 

 liar structure of the leaves. Carpenter (7th edition, 

 1891,p.912)saysof these markings: "Acurioussetof 

 organs has recently been discovered in the antennae 

 of many insects, which have been supposed to con- 

 stitute collectively an apparatus for hearing. Each 

 consists of a cavity hollowed out in the horny 

 integument, sometimes nearly spherical, at others 

 flask-shaped, and again prolonged into numerous 

 extensions formed by the folding of its lining 

 membrane : the mouth of the cavity seems to be 

 normally closed by a continuation of this mem- 

 brane, though its presence cannot always be satis- 

 factorily determined ; whilst to its deepest part a 

 nerve-like fibre may be traced." Fig. 3 shows the 

 cavities viewed from above under a magnification 



Fig. 3. Enlarged view of 

 cavities on lamellae of cock- 

 chafer, seen vertically. 



Fig. 4. Enlarged view of 

 cavities on lamellae of cock- 

 chafer, seen sideways. 



of 1,000 diameters, and rig. 4 the aspect they 

 present when seen partly sideways at the edges of 

 the lamellae. A memoir of the structure by Dr. 

 Hicks is to be found in the " Transactions of the 

 Linnaean Society," xxii. page 147. [We have 

 copied Mr. McGhie's drawings, but we think our 

 readers will find that these censory ©reran s are 

 really pits containing minute papillae. They are 

 generally assumed to be used for swelling. — 

 Ed. Microscopy. S.-G.] Paddle-leg of JDytiscus 

 niarginalis (tig. 0) needs little accompanying 

 notice. Dytiscus marginalis is one of the best- 

 known of the beetle tribe. A friend of mine, who 

 has a large conservatory containing an artificial 

 pond — the waters of which, by the way. have 

 developed a remarkably rich growth of diatomaceae 

 — found a fine large specimen of the larval form of 

 this formidable insect that was working great 

 havoc among the tadpoles of the aquarium. He 

 kept it alive in a glass jar for several weeks, and 

 we were able to watch its habits. Its fierceness 

 and voracity correspond with its repellent aspect. 

 [This is, of course, the hind leg. which is specially 

 adapted for swimming by the flattening of the 



tibiae and tarsi, and by their being furnished with 

 rows of long bristles. The fore-legs of the males 

 are even more interesting, the basal joints being 

 expanded into broad flat plates, furnished with 

 curious sucker-like discs, which secrete an adhe- 

 sive fluid similar to that in the foot of the house- 

 fly. Figs. 2 and 5 are original photographs from 



Fig. 5. Hind leg of Dytiscus margirialis. 



Nature, for which we are indebted to our friend, 

 Mr. R. C. Nelson. Fig. 5 was taken with a 

 Dallmeyer stereo-portrait lens working at f. 4. — 

 Ed. Microscopy. S.-G.] Acute tubercle in human 

 spleen (fig. (5). — This slide is self-explanatory. A 

 high power is needed to properly display the 

 stained Bacillus tuberculosis. Epidermis of Leaf 

 of Auricula. — This was stripped from the underside 

 of a leaf, treated with dilute nitric acid, and 

 stained and mounted in Canada balsam. Its main 

 interest lies in the glandular hairs, which are best 

 seen with a ^-inch objective, and in the stomata. 



Bemarhs on the Foregoing SYote*. — I have been 

 much interested in some of Mr. McGhie's slides, 

 and always like to see members preparing their 

 own. There are two slides upon which I would 

 offer some remarks. Bacteria in Water. — I would 

 suggest another stain. Logwood is not a good 

 stain for bacteria. Some of the aniline stains, 

 such as methyl blue or gentian violet, give much 

 better definition. A preliminary fixation by heat 

 or absolute alcohol is also desirable. Mr. McGhie 

 would then have no hesitation in mounting them 

 in Canada balsam, as the staining would be very 

 pronounced. Tubercle in Spleen. — I think this slide 

 is- not so self-explanatory as Mr. McGhie believes. 

 I have examined the section carefully with a 

 i-inch oil-immersion and fail to detect any tuber- 

 cle bacilli. The abbreviations at corner of label of 

 slide — which I construe to mean : par. = paraffin, as 

 embedding agent ; al. car. = alum carmine, as stain ; 

 Or. = oil of origanum, as clearing agent ; C.B. = 

 Canada ba'sam. as mounting medium — represent a 

 method of preparation not calculated to demon- 

 strate tubercle bacilli. The nuclei of the tissue 

 are well stained, and the tubercle, which in the 

 spleen is always secondary to tubercle elsewhere, 

 is seen as miliary granulations, but no bacilli are 

 visible. The bacilli are not readily stained in 

 tissue such as this. The Ziehl-Neelsen method is 

 the best. The special advantage of this method is 

 that not only does it demonstrate the tubercle 

 bacilli, but it is at the same time diagnostic, as no 

 other bacilli are stained in this way except the 

 bacilli of leprosy. The method is as follows : The 

 sections are transferred from weak spirit to carbolic 

 f uchsine stain for fifteen minutes, then decolorised 

 in weak sulphm-ic acid (sulphuric acid. 10 c.c. ; dis- 

 tilled water. 30 c.c), and afterwards rinsed in 

 GO per cent, alcohol and washed in large quantity 

 of water to remove the acid. The sections may be 

 then counterstained with methvl blue, then de- 



