NEW MICROSCOPES—SEIDEL AND WINTER 199 
it is possible to obtain greatly increased resolution and magnification. 
As a matter of fact, resolution up to 20,000 or 25,000 diameters may be 
realized, and increased magnifications beyond this point up to 100,000, 
even 200,000 diameters, can be obtained, such magnifications, however, 
constituting enlargement of the image. (Definitions of “resolution” 
and “magnification” discussed under “The Ordinary Microscope.”) 
This high magnification is greatly desirable since otherwise the eye 
would be unable to distinguish the fine detail of internal structure at 
a resolution of the order of 25,000. Asa result of this increase in reso- 
lution and magnification over that of the ordinary light microscope 
which is between 1,600 and 2,500 diameters and in the ultramicroscope 
between 2,500 and 5,000 diameters, many surface cells and much intri- 
cate internal structure hitherto unsuspected, or at least undetected by 
ordinary microscopes, have been revealed. To cite a few examples: 
The streptococcal cells appear, not as individual cells, that is, sepa- 
rate and apart from one another, but as chainlike groups, the cells in 
each chain being bound together apparently by the strong rigid mem- 
brane or outer cellular wall which extends over a number of these cells 
and which is so plainly evident under the electron microscope. Sub- 
jected to sonic vibraticn, these cells suffer a loss of protoplasmic mate- 
rial from their interior, causing them to become mere “ghost” cells, 
which makes them more transparent to electron beams. That there 
exists considerable difference between the surface structure and in- 
ternal composition of these cells has also been determined and 
demonstrated. 
Using the electron microscope, Dr. Harry E. Morton, of the depart- 
ment of bacteriology of the University of Pennsylvania Medical 
School, and Dr. Thomas F. Anderson, of R. C. A. Research Labora- 
tories were able to demonstrate that in at least one instance where 
chemical reaction is induced by bacteria this reaction takes place 
“inside” the cells. The fact that diphtheria bacilli reduce potassium 
tellurite to metallic tellurium has been known for some time, but 
whether this reaction occurred inside the cell or on the cell surface 
or both had never been definitely shown until the electron microscope 
was made available. Then, obtaining unstained preparations of 
Corynebacterium diphtheriae grown on blood infusion agar, Drs. 
Morton and Anderson demonstrated that the typical polar granules 
appear as dense spherical masses, or possibly plates, of a very black 
color and that in unstained preparations of this same Corynebacterium 
diphtheriae grown on potassium tellurite chocolate agar, not only the 
polar granules are in evidence but also the tiny needlelike crystals 
inside the cell which disappear along with the black color of the cell 
masses when a drop of bromine water is added to 1 ce. of a suspension 
619830—45——14 
