83 



Do not be misled into thinking that low power work is all 

 that is necessary. For much useful work objectives from 4m. 

 to -|in. suffice, but many times I feel the need of objectives of 

 higher power than Jin. A good substage condenser is a 

 desideratum, and a Baker Nernst electric lamp furnishes a good 

 source of light, since the light is powerful enough to penetrate 

 comparatively dense structures which it is not always easy to render 

 transparent without causing damage to other more delicate 

 structures in their vicinity. In fact, the lepidopterist can do with 

 as good and full a stand as he can afford. 



The like applies to his microphotographic apparatus. The 

 better it is the better his works, but here I may say at once that 

 usually his longer focus lenses will be the more useful, relying on 

 his extension for his size. 



Photographs may usefully be recorded in the same books as 

 your microscopic slides, giving lantern slide number and negative 

 number. Houghton's "Negasys" file to keep the negatives ; n 

 is the best. 



Dissections. 



A serious worker must make a number of these of every 

 insect. The series he makes may be as extensive as he can find 

 time and material to ma~ke. Variability is present in structure as 

 well as colour and often serves to bring out atavistic characters, 

 throwing light on the phylogeny of the species. The dangers of 

 drawing conclusions from single preparations can hardly be too 

 strongly emphasized. 



For beginners nothing is more helpful than to take such a 

 book as Comstock's Manual or Folsom and work quietly through 

 the diagrams with such material as may be at command. Folsom 

 contains a very valuable Bibliography which, as the worker 

 advances, will open up to him a wealth of literature bearing on the 

 problems he is studying. 



Lastly, I would recommend every worker at Entomology to 

 join the Entomological Society of London, which has a remark- 

 ably fine library available to members, and whose transactions are 

 of world-wide authority. 



AVES. 



I must deal with these in less detail. 



Procuring specimens consists, I am sorry to say, of killing 

 them, but my recommendations are a series of " don'ts." 



Don't kill a bird unless you want it. As a rule there is no 

 necessity at all to kill, as the ornithologist is overwhelmed with 

 excellent works with beautiful plates of nearly every British, bird. 

 In fact, it is an embarras de richesses. Don't kill a bird unless 

 you are sure you can either preserve it or get it preserved before 

 it goes wrong. 



