148 



HA RD Wl CKE 'S S CIENCE ■ G SSIP. 



the floor of an ancient sea, arid were afterwards up- 

 heaved and converted into a mountain-chain, whose 

 rocks lay inclined at a steep angle. This mountain- 

 chain was subsequently lowered until seas covered 

 its highest summits, and deposited beds of chalk, 

 London clay, &c., which ultimately buried them up 

 to the depth of more than a thousand feet. 



J. E. Taylor. 



APPEARANCE OF CRYSTAL FORMS IN 

 MOUNTING MEDIUM. 



THOSE microscopic readers of Sciexce-Gossip 

 who read my paper on ' ' Damar as a Mounting 

 Medium," in the November number of last year, will 

 remember the high terms in which I spoke of it as a 

 substitute for balsam. As I have found from several 

 kind letters and slides received, that many others are 

 of my opinion, I wish now to call attention to a most 



Fig. 133. First Appeanince of 

 Small Crystals in Damar. 



Fig. 134. Second .-Appearance 

 of ditto. 



remarkable and aggravating appearance that has 

 come under my notice within the last few weeks. 

 Let me remark at the commencement, that though 

 what I am going to describe is (as all who read this 

 wjll, I feel sure, agree) annoying to me personally, 

 still no brother microscopist with whom I am ac- 

 quainted has experienced anything of a like nature. 

 As you will see by reference to the paper mentioned 

 above, I have used damar in mounting for some con- 

 siderable time, and you will also see the method I 

 adopt in mounting with it. Some four weeks ago I 

 mounted a slide of a spiracle of a Privet Hawk-moth 

 larva for a friend, who remarked, on receiving it, 

 that there was a peculiar, scratchy appearance seem- 

 ingly between the slide and thin cover. On looking 

 myself, I remarked that it was a scratch on the glass, 

 and so the matter ended for the time. About a 

 fortnight since, however, I was examining a slide of 

 Sphturaphides which I had mounted a few days 

 before, when I was surprised to observe the same 

 appearance of scratchiness that was noticed by my 

 friend in the spiracle slide, except that, whereas in 

 that only two or three scratches were visible, here they 

 were fast covering the slide, and obliterating almost, in 

 many cases, the Sphneraphides. I at once saw that 

 these forms were no marks on the glass, but decidedly 

 some chemical property either of the object or of the 



fluid. As I had been mounting other slides at the 

 time, I at once examined them, when I found, to my 

 annoyance, all showed signs of the crystal forms ; 

 one slide in particular, the mandibles of a house 

 spider, which I had mounted for a friend rather 

 successfully, I was vexed to find almost surrounded 

 by the crystal form, some large, some small ; and 

 since then they have quite covered part of the object. 

 Had the crystals made their appearance in animal 

 preparations only, I should have thought that the 



Fig. 135. Crystals in Damar, seen under higher power. 



Fig. 136. .\nother set of ditto. 



liquor potasso; or turpentine with which they were 

 prepared had had somewhat to do with it ; but 

 vegetable and animal preparations shared the same 

 fate ; so I at once came to the conclusion that the 

 damar must be the cause. 



The tube of damar that I am now using has been 

 employed in the mounting of many slides, and all, 

 with the exception of those mounted within the last 

 two or three weeks, are as clear and good as any one 

 could wish. The peculiar thing is, then, what is the 

 cause of the damar only recently producing these 

 crystals? In order that I might be certain that the 



