98 



HARDWICKE'S SCIENCE-GOSSIP. 



and perseverance only are required. The manage- 

 ment of light, the degree of amplification required 

 to see an object to the best advantage, even the use 

 of the drawing materials may be self-taught ; possibly 

 a struggling young microscopist may learn more by 

 half an hour's direct teaching than he could gain in a 

 month's groping by himself, but in the end, experi- 

 ence is the best master. A temptation to avoid is 

 drawing upon the imagination ; by this is meant 

 repairing broken or distorted parts, imagining what 

 might but never could be — building up a perfect 

 diatom from a fragment. Dr. Greville in i860 was 

 very clever at this sort of work, no one could ever 

 hope to see half the objects depicted in his plates ; 

 better far draw imperfections, if they teach anything, 

 and often a broken or misplaced tissue affords a very 

 valuable lesson. In microscopical drawing there 

 must be no exaggeration. It is sufficient to observe, 

 study, and convey to paper the actual thing before 

 you. Favourite subjects are the various parts of 

 insects, especially the head and its appendages. How 

 best to see them ? Certainly not distorted between 

 flattened glasses. A very popular object is what is 

 called the "foot" of dytiscus ; before the days of 

 binoculars, this was fairly well prepared by Topping 

 — in a perfectly flat condition. Considering that its 

 salient point is the beauty of the "cups" it was 

 simply imintelligible until seen as an opaque object, 

 fresh from the insect, gummed to a cork slide — 

 without covering glass. It is a great advance that 

 our modern preparers, with admirable skill, now 

 mount parts of insects in fluid, without crushing them 

 out of knowledge into an unmeaning mess. The 

 young microscopist might here be advised to limit 

 the contents of the " cabinet " to purely typical slides 

 or those requiring actual preparation. There can be no 

 advantage in admitting anything dried and desiccated, 

 which can be procured fresh and living at each 

 recurring season — the woods, the garden, and the 

 stream are the best cabinets. There seems no limit to 

 the appetite for slides ; even Volvox glohator has been 

 "mounted" ! 



For drawings, fresh objects are desirable : lichens, 

 fungi, eggs of insects, anthers and pollen of flowers, 

 seeds, all parts of insects never look so well as when 

 simply attached with a smear of gum to a slide of 

 cork, and uncovered, illuminated with the speculum. 

 Take a subject as a type, say the head of Saltiais 

 scenicits, a common ground spider ; it has grand eyes, 

 in three series. The front row on the edge of the 

 cephalothorax, or forehead, reveals four "oculars" 

 touching each other in a parallel line — the largest 

 pair in the middle. The head should be arranged as 

 soon after death as possible ; front view in this posi- 

 tion, it seems " actually leering at us " with weird and 

 ghastly reality. To paint this portrait is worthy the 

 best eifort of the greatest artist, for nothing can be 

 finer in character or colour ; with a little management 

 it might be arranged to be seen alive. This is a good 



lesson, as it proves that subjects for drawing are very 

 accessible. It is worth while, or the purpose of good 

 work to remove the covers of prepared opaque 

 objects, especially when there is any tendency to 

 clouding on the under side of the covering glass. 



Of pigments, opaque colours should be avoided, for 

 instance, Vandyke brown * is difficult to manage, and 

 unsuited for delicate work. A colour or tint often 

 required for microscopical work is the beautiful rich 

 tone of the chitinous parts of insects ; this can be made 

 by an admixture of burnt and raw sienna, warmed 

 with carmine, or rose madder. When a wash of this 

 is thoroughly dry, and its inequalities lightly stippled 

 with Payne's grey, the exact complexion of the insect, 

 making allowance for lights and shades, will be ob- 

 tained. In all water-colour work, a rule to I'emember 

 is, never go over a wash a second time until the first 

 be perfectly dry ; this applies also to stippling. 

 Stippling should show granulation, which is lost 

 if the touches are allowed to run into each other. 



E. T. D. 



Crouch End. 



A MORNING'S STUDY OF A FISSURE 

 NEAR TENBY. 



TENBY to the naturalist is the queen of Welsh 

 watering-places ! Nature in this part of 

 Pembrokeshire deals out her gifts with no niggardly 

 hand. The cliffs and adjacent country are clothed 

 with beauty and variety ; the botanist and zoologist 

 find there a wide field for their labours. The geologist 

 meets with still more encouragement, for Nature here 

 exposes to his eager ken several slices, as it were, of 

 her different formations, ranging from the Silurians 

 up to the coal measures, each of which is a repast 

 that will more than satisfy a life of application. 

 Organic remains are not uncommon, from the ferns of 

 the coal down to the trilobites of the Silurian rocks. 

 The waters that bathe the coast contain marine life 

 in abundance ; treasures, some of which are hoarded up 

 in the cabinet of the shell-collector, or are minutely 

 examined by the microscopist, others of which are dis- 

 sected with ever-increasing knowledge and pleasure by 

 the student of biology. On one side of Tenby runs a 

 line of sand dunes — ever-shifting bulwarks raised by 

 the inconstant wind against the siege of ocean — on 

 which are to be found many beautiful land mollusca. 

 Here and there their empty tenements have been 

 gathered together by the wind, in time to form 

 groups of fossils in sandstone — maybe to be disturbed 

 in their quiet resting-places ages hence by future 

 palaeontologists ! 



There are human landmarks as well. Cave dwell- 

 ings show that pre-historic man was no stranger here, 



* Vandyke brown is made from ground-up Egyptian mum- 

 mies. The great colourman of Long Acre uses up an individual 

 every few months. 



