99 THE MICROSCOPE. June 
is probably explained by the fact that some one having a 
suppurating wound had handled the cans, thus causing the 
infection. The coldness of the ice is not injurious to these 
minute forms. ‘They yield to heat but not to cold. Some 
people boil water to purify it and then cool it with ice 
thus reducing the dangers considerably. 
Correction. In Professor Hyatt’s article on page 67, 
line 21 for ‘“Holding the brush” read: Holding the slide. 
In 3d line from bottom of p. 67, read bran for “‘loan.”’ 
PRACTICAL SUGGESTIONS. 
By L. A. WILLSON, 
CLEVELAND, OHIO. 
Skill needed.— This instrument is an extension and 
enlargement of the vision only. With the instrument 
alone, we can discover nothing. The brain behind the 
machine does the work. In proportion as this brain is 
cultivated will the manipulation be advanced. For exam- 
ple, it would be wicked for an ordinary microscopist to 
swear that a certain specimen of blood was human blood 
and not dog’s blood; yet it is claimed that experts, who 
have devoted their lives to such measurements, can safely 
attest the kind of blood. A species of lichen can often be 
differentiated from an allied species by the measurement 
of the spores when corroborated by other particulars. 
Purchasing an Outfit.—We must crawl before we can 
walk and we must lisp in the accents of childhood before 
we can speak with the voice of aman. So it is with buy- 
ing an outfit. A beginner should buy a good stand, with 
a society screw and a substage ; and start with low power 
objectives. As knowledge and facility of manipulation 
grow upon him he will naturally procure higher powers 
and substage arrangements. 
What shall we look at?——All nature is now alive, the 
plants, the ponds, the lakes, the woods, everything is teem- 
ing with minute life. It is impossible to turn without find- 
ing something interesting or beautiful. He will see the 
most who choses some special branch of natural science 
