March 1, 1867.] 



HARDWICKE'S SCIENCE-GOSSIP. 



59 



surface is uneven, and believe that its irregularity is 

 the result of both upper and lower membranes 

 being folded into a number of minute pleats or 

 wrinkles, which have a tendency to overlap each 

 other— a difference in detail only, not in plan, 

 between these markings and those on the scales of 



Fig. 50. Scale of Podura, unknown species, x 450. 



all other insects. This is best shown by oblique 

 illumination ; but when the illuminating ray is in a 

 direction corresponding to the axis of the micro- 

 scope the appearance is totally changed, and the 

 wedge-shaped markings, which I believe to be 

 hollows between the pleats or corrugations (and 

 not particles, as stated in the " Micrographic 

 Dictionary" and elsewhere), come into view directly. 

 Their dark outlines, I think, represent the shelv- 

 ing sides of the little pits, and the bright space in 

 the centre of each is the deepest portion, which 

 from its position with regard to the ray, obstructs 

 the least amount of light. 



By moving the diaphragms of Powell's condenser 

 a little backwards and forwards, so as to obtain 

 alternately direct and oblique light, the appearances 

 represented in the figure attached are given. The 

 conclusion I have arrived at seems still further 

 supported, if one of the most strongly-marked scales 

 be examined with a £th objective, and Smith and 

 Beck's patent illuminator for opaque objects under 

 high powers. The wedge-shaped markings are then 

 distinctly seen to be little pits. 



Opaque illumination by means of the side-con- 

 densing lens and a |th object-glass shows the tops of 

 the ridges of pleats illuminated, and the spaces 

 between in very strong shadow, provided the beam 

 of light strike the scale sideways. If it strike 

 lengthways, the view is too indistinct to be satis- 

 factory. My opinion on the subject differs slightly 

 from that of Mr. Beck, who regards the wedge- 

 shaped markings as elevations, and argues ac- 

 cordingly. The question as to whether they are 

 hollows or elevations is of no great importance, and 

 it is exceedingly difficult of resolution. Mr. Beck's 

 remarks refer to the test scale. 



S. J. McIntire. 



ANALOGY OF SMELL. 



A N article on the " Analogy of Eorm " in the 

 -"- last number of Science Gossip, brought to 

 my mind the very remarkable instances which are 

 to be found in the Analogy of Smell among the 

 Eungi. I have lately been turning my attention to 

 these interesting productions of nature, and have 

 often been quite astonished at the exact resemblance 

 which the odours of certain species have borne to 

 something extremely familiar to me, but of a 

 totally different nature. 



During the month of October last, as I was 

 ascending one of the rising slopes of the Cottes- 

 wold hills, in the vicinity of Cheltenham, I thought 

 I perceived the peculiar but agreeable scent of 

 Russian leather, and recollecting that there was a 

 fungus reputed to possess that odour, I immediately 

 directed my search for it. Several specimens were 

 growing around me where I stood, and thus I had 

 been led to detect this little white fungus by its 

 scent, as we sometimes do the violet in the spring 

 of the year, before the eye reveals its whereabouts. 



The Rev. M. J. Berkeley says of this species 

 {Hygrophorus Busso-coriaceus), that it is rare ; but 

 I have a suspicion that it may have been overlooked 

 as the young, or a small state of Hygrophorus vir- 

 gineus, which at a distance it somewhat resembles. 

 It may, however, be readily known from that species 

 by its delightful scent alone, which it retains after 

 drying, and to such an extent, that I think it might 

 be made available for the scenting of drawers, &c. 



In the same pasture I gathered Hygrophorus 

 murinaceus, which/possesses the odour of aquafortis 

 — far less agreeable, but perhaps equally remark- 

 able. The collector of the larger fungi is fre- 

 quently reminded of this singular similarity of odour 

 to a series of odd things, both of a disgusting and 

 agreeable nature, as the following brief enumera- 

 tion will illustrate, viz., cinnamon, garlic, helio- 

 trope, cucumber, gas-tar, tarragon, new flour, mice, 

 bugs, ripe apricot, putrid flesh, &c. The similarity 

 of form and colour which some insects bear to 

 portions of the vegetable kingdom, would lead one 

 to suppose that they were designed to protect them 

 from wholesale destruction by birds, &c. ; but as 

 regards the odour of fungi, it seems more difficult 

 to form an opinion. The mycologist, however, 

 often finds that they serve him as valuable aids in 

 the determination of species, and without which, 

 his conclusions might be more exposed to error. 



H. Beach. 



Marks.— A delta is a water-mark; around crater 

 a fire-mark ; and every force which acts on a sur- 

 face makes a tool-mark which may be learned. Each 

 mark is like a letter. It has a form and a meaning, 

 but only for those who learn to read.— Frost and 

 Fire, i'. 



