SCIENCE- G OSSIP. 



309 



Immediately lai'ge quantities of a brown fibrous 

 matter appeared in the water, and the pipes and 

 taps became choked with it. The brown matter 

 proved to be Palndicella, detaclied from the inside 

 ■of the water-mains by the pulsation of the pumps. 

 Mr. Shenton further remarked that the chairman 

 of the Waterworks Committee considered that the 

 removal of the deposit from the pipes had 

 improved the quality of the water ; but he was not 

 sure that this assumption was, from a biological 

 standpoint, a correct one. Certainly a hindrance 

 to the flow of the water had been taken away, but 

 it was well known that the floating and free- 

 swimming foi'ms of life found in potable water- 

 supplies were reduced in numbers by passage 

 through the mains. In the Biston water-supply 

 during 1892 and 1893 observations showed that 

 the reduction in the mains amounted to about 

 ■60 per cent. No doubt sedimentation and death, 

 especially of vegetable organisms dependent upon 

 light for existence, accounted for part of this 

 reduction ; but it must be very largely due to the 

 •consumption of such organisms as food by the 

 animal forms of these pipe deposits, so that the 

 removal of " pipe moss " does not necessarily 

 imply a decrease in the total of living organisms 

 present in the water as delivered to the consumer, 

 and it may mean the reverse. Effectual filtration 

 of the water-supply before entering the mains 

 would, by the removal of floating and free- 

 swimming forms of life, render the existence of 

 the organisms forming " pipe moss " impossible, 

 and keep the mains cleaner than any amount of 

 scraping can do. The organisms alluded to 

 are not pathogenic, or in themselves the cause of 

 disease, nor is their jDresence to be taken as 

 indicative of pollution ; but, while they do not 

 render a potable water unsafe, they may render it 

 unpalatable. 



Mounting in Glycerine Jelly. — I venture to 

 send you the following note on this subject, in the 

 hope that others of your readers who have had 

 experience in the same direction may be induced 

 to express their views. During the past twenty 

 years I have mounted more than a thousand slides 

 of mosses and liverworts, sometimes in one medium 

 and sometimes in another, but generally in glycerine 

 jelly, as being, on the whole, the most satisfactory. 

 My usual course has been to first soak the specimen, 

 for at least twenty-four hours, in a mixture con- 

 sisting of water 1^ oz., alcohol l|oz.,and glycerine 

 5 drachms, and then to mount on the ordinary 

 glass slide in glycerine jelly, which of late years I 

 have always made myself, and to seal the edge of 

 the cover-glass with cement of some kind, prefer- 

 ably copal varnish thinned with benzine. From 

 time to time, however, some of my slides, after 

 standing for perhaps several years, have gone 

 wrong, though others have never altered ; for in- 

 stance, I have some that were mounted in 1882 

 which are as good now as the day they were put up, 

 while others that only date from 1893 have recently 

 developed beads of glycerine round the edge of 

 the cover-glass, a sure sign of the jelly having 

 degenerated. 1 have been at some pains to find 

 out the cause of the mischief, though this is not 

 easy to do. My experience, however, leads me to 

 think that the following points are important. 

 The slides should not be exposed to draughts or 

 extreme cold ; the preparatory fluid should be well 

 removed from the specimens by means of blotting- 

 paper before mounting ; no pressure should be 



applied to the cover-glass while the jelly is liquid, 

 either to eject supeifluous jelly or to keep the 

 cover-glass in place ; a ring of jelly should be left 

 outside the cover-glass, and the slide should then 

 stand for at least two or three months before the 

 extra jelly is removed and the cover-glass cemented. 

 Some four or five years ago the use of formalin 

 with the jelly was suggested to me; but, though 

 I mounted two or three slides thus at the time, 

 it is only quite lately Ihat I have followed out the 

 suggestion in any detail. During .the past few 

 weeks, however, I have used a very small drop of 

 formalin, mixed with the jelly, in all the mounts I 

 have made, and am very much struck with the 

 apparent usefulness of the recipe. The formalin 

 causes the jelly to set so firmly that the applica- 

 tion of even a fair amount of heat afterwards does 

 not seem to liquefy the jelly again ; indeed, the 

 chief difliculty of the process lies in the fact that 

 the jelly sets so quickly. The presumption is 

 thus raised in one's mind that the jelly in this 

 form may be all the more durable. It occurred to 

 me that possibly the formalin might have an in- 

 jurious effect on vegetable tissue, so I tried soaking 

 some leaves of Spliagnum ovsjndatvm in the pre- 

 paratory fluid, then adding formalin, and, after 

 allowing the specimen to soak in this for twenty- 

 four hours, mounting as above. I found that the 

 delicate structure of the leaves was in no way 

 affected. I feel that my acquaintance with this 

 method of mounting" has been so comparatively 

 recent that it is impossible for me as yet to form 

 a reliable judgment. It would, therefore, be a 

 matter of great interest to me, and doubtless to 

 others, to have further information from those 

 who have used formalin for a longer period. I 

 may add that slides of Andreaea alphia (mounted 

 in 1896), Hypnum coimnutatitm and Cephalozia 

 Mcuspidata (mounted in 1897) are still in a state 

 of perfect preservation. — T. H. Russell, 17 Vicarage 

 Road, Edcjbaston, Birminglxam. 



[Formalin has the property of rendering gelatin 

 practically insoluble, though not entirely so under 

 certain conditions, which we have recently had 

 occasion to investigate. Not only will the formalin, 

 therefore, render glycerine-jelly mounts (which 

 are, of course, a mixture of glycerine and gelatin) 

 less liable to that deterioration that is always a 

 danger with media made with glyceiine ; but it 

 should preserve them from any tendency towards 

 fungoid growths. The disadvantage of using 

 formalin is not alone, as Mr. Russell says, that the 

 glycerine jelly has a tendency to set too quickly, 

 but also that, in case of any imperfection in the 

 mount, it is impossible to subsequently melt the 

 mountant and remount the object. Formalin is 

 an excellent preservative, its chief drawback being, 

 so far as our own experience goes, its liability to 

 cause shrinkage, especially with regard to animal 

 life. We do not think this would apply to mosses 

 and similar structures. It is scarcely necessary to 

 add that the formalin must be added to the mount 

 the last thing, and by no means to the glycerine- 

 jelly bottle. We may add, in passing, that any 

 tendency to fungoid growth in the latter can be 

 obviated by the addition of a few drops of some 

 essential oil, such as oil of cloves. — Ed. Micro- 

 scopy, S.-G.] 



Beck's " Imperial " Microscope. — Messrs. R. & 

 J. Beck, Limited, have of late years devoted their 

 attention mainly to improving their students' class 

 of microscope, the latest type of which, the 



