1876.] Proceedings of Societies. oT1 
ever from these rocks were of interest. The three cycloid fish scales, 
and a few detached caudal rays, in the fragments of red shale presented 
by him this evening, he found on the Perkiomen Railroad, near Yerkes 
Station, Montgomery County. One of the scales resembles those de- 
scribed by the late Professor E. Emmons, under the name of Rabdiolepis 
elegans, from the mesozoic coal shales of Chatham County, N. C. 
Mr. Redfield called the attention of the members to the volume of 
letters of Zaccheus Collins, belonging to the Academy, which had been 
recently arranged and bound by him. The volume contains an unbroken 
series of sixty letters, from Rev. Henry Muhlenberg, of Lancaster, to 
whom American botany has been so much indebted ; also, a correspond- 
ence with his son, Fred. Aug. Muhlenberg, in which we find the history 
of the transfer of the Muhlenberg Herbarium to the American Philo- 
sophical Society. 
There are also numerous letters from Stephen Elliot, Dr. Jacob 
Bigelow, Dr. William P. C. Barton, Dr. William Baldwin, Nuttall, 
Torrey, Leconte, Sr., and many others well known to the scientific 
world. It cannot be expected that these letters of sixty years ago can 
add any new botanical facts to our stock, but they have great interest as 
illustrating the early history of botanical science in our land, and as re- 
vealing to us the obstacles which the student of that day encountered in 
the searcity of books and in the difficulty of communication. 
Professor Frazer spoke of thinness or minuteness of objects under 
the microscopic and suggested method of studying, by means of the 
fluorescent ray, objects at present invisible to the highest powers. 
r. Hunt stated in reply that microscopists were not willing to be 
limited in their observations by the calculations of mathematicians, and 
that the comparative darkness of the fluorescent ray would not be favor- 
= able to investigations of the kind. 
In continuation Dr. Hunt spoke of the destruction of potato-starch 
by the fungus causing the potato-rot, and stated that he had observed, 
under the microscope, the absence of starch in the cells attacked by the 
Peronospora, although the fact of such invasion being productive of the 
result described had been denied. 
Mr. Thomas Taylor, of the Department of Agriculture, spoke of the 
effect of frost upon potatoes, and stated that he had found starch at the 
end of twelve months in frozen tubers. He also observed that the 
Potato fungus would grow in cells devoid of starch, but he had not ob- 
Served the destruction of granules by the cause referred to. 
May 16th. Mr. Thomas Meehan said that what was popularly known 
as the “sleep of plants,” the closing of some kinds at night-fall, though a 
Matter within common observation, had not, so far as he was aware, 
n made a subject of physiological investigation, with the view to 
‘seertaining the value, if any, of this kind of motion in the economy of 
Plant life. He had recently discovered that by means of this peculiar 
Sat ACH ao 
