34 
The President's Address. 
powers has been brought to great perfection by Captain 
Edward Curtis, assistant-surgeon U.S. Army. Dr. Maddox 
published in the 6 Intellectual Observer’ for July a descrip- 
tion, accompanied with illustrations copied from the original 
of Captain Curtis’s photographs of the Pleurosigma angu- 
latum , one being taken with an American objective of 4 th 
focal length, and another ;with a -Ajdh of Powell and Lealand, 
the former being worked to an equal power with the latter 
by means of an achromatic concave amplifier used instead of 
an eye-piece. In these photographs, hexagonal markings 
appear with powers of 2344 and 2540 diameters, and nearly 
circular markings with magnification of 19050 diameters. 
In the August number of the f Intellectual Observer, ’ Dr. 
Maddox published a description of the process employed, 
from which it appeared that Captain Curtis used a Silber- 
mann’s hcliostat, and that the light was transmitted through 
a cell containing a saturated solution of ammonia-sulphate of 
copper, and thus rendered approximately monochromatic. 
At one of our recent meetings, Mr. How exhibited, by 
request of Dr. Maddox, a beautiful series of Captain Curtis’s 
photo-micrograplis obtained with various powers. 
It is impossible not to admire the truly scientific and 
disinterested spirit which led Dr. Maddox to bring what 
might be considered rival work before the English public. 
But while assigning a very high degree of merit to the pro- 
ductions of Captain Curtis, it is only just to remark that in 
many cases, where his labours and those of Dr. Maddox have 
taken parallel lines, the high reputation of the latter has on 
the whole been fully maintained. 
In the application of the microscope to natural history 
investigation during the past year, much worthy of notice 
has been achieved, if no very remarkable discoveries have 
been made. One paper, though properly belonging to an 
earlier period, was only made known to the English student 
by a translation which appeared in the f Annals of Natural 
History’ for March, 1866 ; and it is now alluded to on account 
of the important lesson which it teaches of the necessity of 
examining the delicate structures of soft creatures without 
disturbing their normal condition. Professor Schjodte de- 
monstrates in this paper that the louse (pediculus) has a 
suctorial, and not a biting mouth, as was often stated. He 
found that the common practice of flattening the organs of 
this creature under glass gave rise to completely false 
appearances, and that it was only by surveying the parts in 
their natural condition that the true structure could be 
ascertained. 
