128 THE MICROSCOPE. Aug. 



PRACTICAL SUGGESTIONS. 



By L. A. WILLSON, 

 CLEVELAND. OHIO. 



Algae on a Sidewalk. — Noticing a bright green stain over 

 man}^ of the flagging stones in front of my house, I scraped up 

 a small portion and placed it on a slide. A dissecting 'scope 

 revealed that the material was too full of sand and grit to ex- 

 amine with a larger instrument. I therefore flooded the mass 

 with water and with needles separated from the specimen as 

 much of the sand and grit as possible. With a pair of forceps 

 I then picked up the green mass and passed it through water 

 and then removed it to a clean slide and with the forceps 

 picked out the few particles of sand and grit remaining. I 

 then had a very pretty slide of filamentous alg^e. I account 

 for its presence on the flagging by the fact that it is constantly 

 watered with Lake Erie water which is always charged with the 

 spores of the alg^e. They may be permanently mounted in a 

 solution of hydrate of chloral and will retain their refreshing 

 green color in that medium. 



Seeing Bacillus Tuberculosis with a Low Po^ver. — If 

 properly stained this object can be seen nicely with a one- 

 quarter inch objective. All that an amateur would care to see 

 can be thus exhibited. If stained red on a blue ground it will 

 appear plainly and beautifully. 



A Convenient Sub-stage Condenser. — A perisco^iic eye- 

 piece set in the sub-stage with an adapter will afford a very 

 good sub-stage condenser. 



Polarizers are usually fitted with an adapter which may be 

 removed and used with eye-piece in the sub-stage. The con- 

 denser certainly improves the performance of the microscope, 

 it renders the light more pleasant to the eye and better defines 

 the objects. Often, things hardly visible without the condenser, 

 for example, bacilli tuberculosis, become distinct when it is em- 

 plo3^ed. With low powers the condenser should be moved 

 down away from the objective and with high powers brought 

 up close to them. No one who has ever used a condenser 

 would be without one. The light is also much improved by 

 using a microscopic lamp with a blue glass inserted in the 

 bull's eye. 



