56 
PROCEEDINGS OF SOCIETIES. 
existence of such vegetable growths is no evidence that epiphytes have 
any essential connection with cases of diphtheria.” In Beale’s ‘ Micro- 
scope in Practical Medicus,’ page 188, he says : “It is true that in 
many cases sporules of fungi are met with, hut many circumstances 
prove satisfactorily that they merely grow in the false membrane as a 
nidus favourable to their development, and are not to be regarded 
as the cause of its production.” On the page opposite this paragraph 
he has two figures, neither of which shows any fungi. 
This fungus theory was revived in Germany a few years ago, and 
they made use of salicylic acid to destroy the fungi ; they have aban- 
doned this, however, and are now using, as a local application, warm 
water and steam. The Doctor concluded with the statement, that 
“ the generally received opinion in the medical profession, at the pre- 
sent time, is that it is constitutional in its nature, and I think micro- 
scopic observation does not prove the contrary.” 
The remarks of Dr. Mouser being so essentially in opposition 
to those expressed by Dr. Edwards at a former meeting, the latter 
gentleman was requested by Dr. Woolsey, of Oakland, who seemed to 
favour the fungoid theory, to say a few words on his side of the ques- 
tion. Doing so, he alluded to the fact of the microscope being the 
only instrument able to decide the question, and then when used by 
careful illumination and manipulation, with powers of one thousand 
diameters and upward. He believed that diphtheria was local in the 
beginning, and spread by fungoid growth, and explained what he had 
seen, as well as others who had made the matter a study, in the way 
of watching the growth and development of the fungus. He used the 
black-board to explain the subject, and certainly convinced all present 
that his faith was firm regarding his theory, and that he believed the 
proper use of salicylic acid would destroy the fungus and cure the 
disease. 
After an interchange of general conversation, the matter of illu- 
mination came up while examining the markings of some of the 
diatoms presented earlier in the evening ; and as Dr. Edwards is not 
only an authority on diatoms, but has naturally made the study of 
the best method of bringing out their beautiful peculiarities very 
thorough, he was requested to state to all what he had to one or two 
privately regarding the blue ray in microscopy. 
With a few remarks as a preface, he proceeded at length to explain 
and illustrate a matter which he stated he considered of great interest 
and extreme importance to every member as a working microscopist, 
namely, the character of the mode of illumination made use of in 
viewing more particularly the finer so - called “ test - objects,” the 
Diatomaceae. His first experiments were made in the summer of 
1863, when he was endeavouring to improve the modern achromatic 
objective. The results were made public at meetings of the American 
Microscopical Society, November 1865, and subsequently. He first 
found that, when using two objectives of the same power and 
angular aperture on the same object, with one he had to use a greater 
obliquity of the illuminating beam than the other to obtain the same 
result. If now a piece of blue glass were interposed in the course of 
