268 Proceedings of Scientific Socteties. { April, 
PROCEEDINGS OF SCIENTIFIC SOCIETIES. 
ACADEMY OF NATURAL SCIENCES OF PHILADELPHIA, BIOLOGI- 
CAL AND MiIcroscoPicAL SECTION, Philadelphia, January 21, 
1878.—-Dr. R. S. Kenderdine in the chair. Mr. Ryder related 
some observations which he:had made on the residual image in 
the retina, as to the changes of color it undergoes, and as to 
the length of time it remains after the real image has ceased to 
excite the retinal cones and rods. The matter was discussed at 
length by Dr. Seiler, Messrs. Zentmayer, Perot and Ryder. 
Mr. Potts then made an interesting communication on carniv- 
orous plants. In the course of his remarks he gave a full descrip- 
tion of the Drosera, Dionea and Nepenthes. Of the latter he 
showed two preparations of the pitchers, one mounted flaf in bal- 
sam, and the other in a deep cell filled with benzole, both stained 
with hematoxylin. These beautiful preparations showed the 
peculiar distribution ‘of the spiral vessels and excreting as well as 
absorbing glands. Mr. Potts called particular attention to the 
fact that the spiral vessels in this plant consist of four fibres, and 
o not anastomose, even in the midrib of the leaf, but are 
collected in bundles and run alongside of each other. He also 
described the peculiar openings of ducts along the serrated and 
He set forth the advantages of the new instrument as 
combining steadiness, convenience of manipulation and smallness 
of cost, which latter is generally an important item with students 
of minute vegetable and animal anatomy. 
Dr. McQuillen made some interesting experiments upon reflex 
nervous action as illustrating Pfluger’s laws. Further remarks 
University of Pennsylvania, adapted to the wants of his botanical 
l 
native of Australia and the East Indies. The insects had been 
thoroughly digested, not a particle of soluble organic matter OF 
protoplasm was left inside the external shell of chitin, which 
orms the covering of the creatures. The specimen was therefore 
a very instructive one, as illustrating how completely carnivorous 
these plants have become. The most interesting part of their 
structure is the presence of the honey-secreting glands on pr 
outside which attract the ants, whieh, when they venture sti 
further up the pitcher, finally are bold enough to crawl up i n 
its mouth, never more to return, and to be drowned, digested ang — : 
appropriated to nourish the structures of the invidious destroyer. — 
See aD O CES Uh OS he a a a CR eT NRE Og ae eee 
