ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
91 
is, from the time it was established in the schools in, say, 1840 to 1880, 
has been without a condenser. Not only did those who used the con- 
denserless Microscope consider the condenser an unnecessary appendage, 
but they looked down upon it and regarded it in the same category as 
one of the multitudinous appliances that are packed in such a wonderful 
manner in the apparatus cabinet of a Microscope made for exhibition. 
In 1880 a change came from two separate causes — first, the rise of 
bacteriology : secondly, the introduction of a cheap chromatic condenser 
by Abbe in 1873. 
Taken by itself, the introduction of the Abbe condenser had not 
much effect, but as Zeiss’s Microscopes had for some time been dis- 
placing the older forms, and when the study of bacteriology arose, 
oil-immersion objectives of greater aperture than the old dry objectives 
(especially those of the histological series) were used, illumination by 
the mirror was soon discovered to be inefficient, so a condenser became 
a necessity. The cheap Abbe condenser was the exact thing to meet the 
case. 
Since 1880 the percentage of educational Microscopes, medical or 
otherwise, without condensers, has been daily on the decrease. There 
has not been, during the 'past history of the Microscope, a more 
marked change of opinion with regard to any apparatus than that 
which has taken place in connection with the condenser. 
It is worthy of notice that this change of opinion has been so 
complete that those who formerly condemned all condensers now look 
upon the Abbe chromatic (probably the worst condenser ever con- 
structed) as a distinct advance in microscopy ! 
It must be remembered that the end of an educational Microscope is 
not to discover anything new, but to follow the figures given in the 
text-books, and when the text-books kept on the level of the larger 
objects any tube with a piece of glass at either end was sufficient for 
the purpose ; but as the text-books improved and went deeper into the 
structure of things it was necessary that the student’s Microscope 
should be of a better description. For example, as long as the text- 
books wrote about and figured the spiral vessels in the blowfly’s tongue, 
so long the student did not require a Microscope capable of showing the 
cut suctorial tubes. 
As I mentioned above, the “few,” principally dilettanti, had all 
along used a condenser. I myself had not long entered the micro- 
scopical world as a member of the latter class before I found out that 
a condenser was a necessity. Now, as I have used all the kinds of 
condensers that have been introduced, I will give my own history in 
connection with them, as it will be the history of the condenser. 
My first condenser was a Gillett ; this was in power a 1 /4, and it 
had 80° of aperture. The Gillett is practically the first achromatie 
condenser really constructed as such ; before that time • objectives 
were used, the rule being to select that objective which was next lower 
in power to the objective on the nose-piece. The manner of centering — 
for centering was duly insisted upon even in those early times — was. 
so funny that I must recall it. Vertical movement was performed by the 
substage, but the horizontal movement by the Microscope body ! 
The Gillett was an elaborate instrument ; it was supplied with a 
