August, igo6 ] 



KNOWLEDGE & SCIENTIFIC NEWS. 



bacteria, rendering these organisms very easy to photo- 

 graph when the film is prepared from a pure culture. 

 The solution, when diluted, is serviceable for section 

 staining. 



Acetone-celloidin Method of Rapid 

 Embedding. 



F. Scholz places pieces of material not thicker than 

 3 mm. in pure acetone for half an hour. They may 

 then be transferred to celloidin, though it may be 

 necessary to pass certain material through alcohol- 

 ether for 15 minutes. The pieces remain in a thin 

 celloidin solution for 4 to 5 hours, at 37° to 40". They 

 are then transferred to a thicker solution for 2 to 3 

 hours, after which they are placed in thick celloidin. 

 In the last condition they arc submitted to the action 

 of chloroform vapour, in a closed \essel. In about 

 14 hours they will be of the consistence of cartilage. 

 The blocks are next further hardened in alcohol for 

 some hours. 



Origin of Parasitism in Fungi. 



Mr. George Massee, in a paper read before tl.2 Royal 

 Society, concludes with three interesting statements as 

 to the origin of parasitism in fungi : (i) The entrance 

 of the germ tubes of a parasitic fungus into the tissues 

 ot a living healthy plant depends on the pressure of 

 some substance, in the cells of the host, attractive to 

 the fungus. In other words, infection is due to positive 

 chemotaxis. (2) A saprophytic fungus can be gradually 

 educated to become an active parasite on a given host- 

 plant, by means of introducing a substance positively 

 chemotactic to the fungus, into the tissues of the host. 

 liy similar means a parasitic fungus can be induced to 

 become parasitic on a new host. (3) An immune plant 

 signifies an individual of the same species as the one 

 on which a given species of fungus is parasitic, but 

 which, owing to the absence of the chemotactic sub- 

 stance in its tissues necessary to enable the germ-tubes 

 of the fungus to penetrate, remains unattacked. The 

 author made a series of experiments to verify these 

 statements, using the expressed juice of leaves as cul- 

 ture solutions, and testing the presence of the chemo- 

 tactic substance by sowing fungus spores on a mica 

 film, in which a hole had been bored, and placing it in 

 contact with the juice. If the chemotactic substance 

 were there, the germinating tube of the spore grew to- 

 wards the hole. He also found that the chemotactic 

 property could be destroyed by the addition of certain 

 reagents, such as a trace of acetic acid, etc. In order 

 to educate a plant to become host to any parasite, he 

 injected into the tissues some substance chemotactic 

 to the fungus. Thus he induced Peiiicillium to invade 

 the leaves of Tradescantia discolor, by injecting into it a 

 solution of cane-sugar. Other saprophytic species 

 were induced to- become parasites on Begonia leaves bv 

 the same method, and after fifteen generations they 

 grew as parasites without any addition of a sugar 

 solution. 



Cheap Glass Lenses. 



A German puljlicalion mentitjns a cheiip and simple 

 way of obtaining large lenses for photographic and 

 similar work, by forming a combination of ordinary 

 watch or clock glasses with water or other suitable 

 liquid. Two glasses, whose edges must be well ground 

 so as to fit closely when in contact, are dipped into the 

 liquid, and removed bodily filled with it. The edges 

 are then wiped dry. and moistened with water-glass, 

 wliii-h, helped with a little hydrochloric acid, sets qu'te 



hard, so that the '' lens " can be freely handled. This 

 process is assisted by the use of a peculiar brush, 

 having two pencils on one shaft. As this brush is 

 passed round the periphery, the front pencil wipes off 

 the superfluous fluid, and the following pencil applies 

 the water-glass. By means of a glass disc and a watch 

 glass, a plano-convex lens can be made, and several 

 other forms are possible. 



New Triple Stain for Cytology. 



Dr. Victor Bonney has devised a modification of 

 Flemming's " Triple Stain,' for cytological and histolo- 

 gical purposes, which gives a sharp differentiation be- 

 tween the various constituents of the nucleus, cyto- 

 plasm, and inter-cellular tissues, and is at the same time 

 simple, rapid, and reliable. The object of Flemming's 

 original method was to combine in the tissues the 

 stains saffranin, gentian-violet, and orange G, so that 

 the chromatin substance of the nucleus should be stained 

 by the gentian-violet, the cytoplasm by saffranin, and 

 the inter-cellular substances by the orange. The 

 method has, however, fallen into some disrepute on ac- 

 count of its uncertainty. Dr. Bonnev's modification is 

 as follows : (i) Fix small pieces of the tissue in acetic 

 alcohol for five to fifteen minutes, according to size 

 {pure glacial acetic acid one part, and absolute alcohol 

 two parts). Dehydrate rapidly in several changes of 

 absolute alcohol. (2) Embed, cut, and mount in the 

 usual manner. (3) Stain for one hour in a saturated 

 watery solution of saffranin. (4) ^^'ash in water. 

 (5) Stain for a quarter of an hour in a saturated solution 

 of methyl-violet. (6) Wash in w ater, and zvipe the slide 

 dry, except that part occupied hy the section. (7) Have 

 ready in a drop-bottle the following solution : To 20 c.c. 

 of acetone add, drop hy drop, a saturated watery solu- 

 tion of orange G, until the flocculent precipitate, which 

 slowly appears on shaking, is just dissolved in excess 

 of the watery solution; then filter. (8") Flood the slide 

 with this solution. .\ cloud of colour immediately 

 comes out, which obscures the view of the section. 

 (9) Pour this off on to blotting-paper and flood again 

 w ith the same solution. The colour cloud being much 

 fainter, the section can be watched. (10) When the 

 section has attained a rather fain' brownish-pink colour, 

 pour off the orange-acetone solution, (ii) Wash in 

 acetone for a few seconds. CThis should be contained 

 in a small glass jar, acetone being very volatile; care 

 should be taken that the section does not dry.) 

 (12) Wash in xylol. (13) Transfer to low-power 

 microscope and see if the proper result has been at- 

 tained. (14) \\'ash in two fresh changes of xylol. 

 (15) Mount in xylol-balsam. 



.Ml chromatic elements, nucleoli, and certain nuclei, 

 such as those of polymorphonuclear leucocvtes, stain 

 a rich violet, chromosomes standing out with peculiar 

 distinctness. The spindle fibres of nuclear mitosis 

 stain a faint pink. The cytoplasm stains a rose pink. 

 The inter-cellular tissue stains a pale yellow. These 

 effects are Ijest seen if the slide be examined through 

 a deep blue screen. The most important factor in the 

 process is the orange-acetone solution. If this is al- 

 lowed to act too long, the whole section is stained a 

 deep yellow, while if it has not acted long enough the 

 .section is blotchy and has a distinct violet tint. If the 

 colours are discharged too rapidlv, the orange-acetone 

 must be diluted with acetone. The reagent deteriorates 

 after a time. 



{CommunicatioHS and Enquiries on Microscopical matters should be 

 addressed to F. Shillington Scales. "Jersey," SI. Barnabas Road. 



Cambridge .'I 



