1893.] THE MICROSCOPE. 31 



The following indispensable features for such a compound in- 

 strument have been named by Dr. Shanks in response to a ques- 

 tion : 



"A compound microscope should have a one-inch or C eye- 

 piece, a joint for inclination. The mirror should swing above the 

 stage so as to furnish a top illumination on opaque objects and a 

 fine adjustment. The rack-and-pinion coarse adjustment is con- 

 venient but not necessary, if the cost must be kept low. There 

 should be two object-glasses — a one-inch and a one-quarter inch. 

 The one-inch glass will give good surface views of opaque objects 

 and good general views of sections. The ^-inch glass will mag- 

 nify sufficiently, and is easier to use than the usual g-inch or p-inch 

 objective. These latter glasses work very closely and require thin 

 sections' for their full utilization. The ^-inch objective should re- 

 solve P. ansridatinn.' 1 '' 



Topics for Study. — As to selection of topics for study, we 

 are able to present the views of two different writers, both ex- 

 perts. Additional directions may be found in many books, some 

 of the best and cheapest of which may be found listed among the 

 advertisements. Dr. Shanks' advice is as follows : 



tw Buy this book : ' iooo Objects for the Microscope,' by M. C. 

 Cooke. It will cost 50 cents and will suggest the examination 

 of many common objects to be found everywhere. As a sugges- 

 tion for some lines of work that young people may do, the follow- 

 ing will be within their abilities : 



%i Study the habits and food-plants of insects, especially those 

 feeding on our vegetables and fruits. The insects may eat the 

 leaves or the fruit, or bore into the bark or wood. Examine all 

 parts of the plant for eggs, worms, or cocoons. Make collec- 

 tions of all of them. Hatch out some of the eg-o-s. Also try to 

 develop the cocoons or pupae. Make notes of every circumstance, 

 date, plant, etc. Do not try to do too much in one year. Select 

 two or three plants for study. .Reliable information in these 

 lines will be gladly received by our State entomologists and bota- 

 nists, who will cheerfully name any specimens sent them for 

 identification. Make pressed and dried collections of the mosses 

 in fruit. Make notes of the localities when found and date. 

 Gather the catkins, etc., of willows and other trees that bloom 

 early before the leaves appear. Gather the leaves later ; then 

 the fruit in earlv autumn. Put them together. Make notes of 

 the different dates, etc. 



" Grasses are easily gathered and easily pressed and dried, and 

 the variety is greater than one would imagine. Make collections 

 of the grasses — when in bloom — and also when the heads or 

 spikes are in full seed. Note also the root, whether it is simply 

 fibrous like an annual, or has an underground fleshy stem like the 

 perennials. 



