468 



i^CIENCE. 



[Vol. II., No. 35. 



on the ventricose part of the shell, but the aperture 

 IS horizontal instead of vertical. They are so abun- 

 dant as to encumber the gills of the host, rendering 

 tliem brown to the eye. An Epistylis from the same 

 host was named E. Niagarae : it is close to E. bala- 

 norum, a marine form. The same writer, at another 

 session, described Cothurnia lata n. s., found on Di- 

 aptomus, and also gave a general account of two inter- 

 nal parasites of the crayfish. 



The first paper Thursday morning was on the 

 effects of division of the vagi on the muscles of 

 the heart, by A. M. Bleile. The object of the paper 

 was the demonstration of nutritive or trophic nerves 

 for the heart, and was a continuation of work re- 

 ported in the Proceedings of the society last year. 



Following this, T. S. Up de Graff described certain 

 fresh-water worms. One, a rotifer, is new: it was 

 named Brachionus Gleasonii. Independent of the 

 spines, its length is 0.145 inch, the front of the car- 

 apace without spines. The posterior edge bears five 

 curved spines : there is one, also, on the dorsal part 

 of the shell, — a peculiar feature. 



The remainder of the session was occupied by 

 short papers, by Francis Wolle, on fresh-water algae, 

 and one by John Krtittschnitt on ferns and their 

 development. 



In the afternoon the session was opened by a re- 

 port upon a standard centimetre, prepared by the 

 U. S. bureau of weights and measures, by W. A. 

 Kogers. The lines of the centimetre are ruled on a 

 plate of platinum-iridium soldered to brass with silver. 

 The report describes the plate, and compares its 

 divisions with a standard. The original basis of this 

 unit is a metre upon copper, prepared for Professor 

 Bogers by Professor Tresca of the Conservatoire 

 des arts et metiers at Paris. The report concludes 

 til us: — 



1. That the centimetre A, measured by the middle 

 defining line, is exactly a hundredth part of the 

 metre des archives reduced to sixty degrees Fahren- 

 heit. It can therefore be safely adopted as the unit 

 in all measures with low-power objectives. 



2. That the second millimetre of the scale is ex- 

 actly a thousaudtli part of the metre des archives 

 when at tlie same temperature. 



The centimetre is now the proi^erty of the society; 

 it having been tendered to it by the national com- 

 mittee on micrometry, and accepted and adopted as 

 a standard or basis for future studies and discussions 

 in micrometry. The scale is in the hands of Dr. 

 George E. Fell. A committee was appointed for 

 securing copies on glass. The rules for its control 

 and use will soon be published. 



After this report. Dr. George E. Blackham read a 

 communication on tlie relation of aperture to ampli- 

 fication in the selection of a series of microscopic ob- 

 jectives. The author showed that amplification is 

 not the only element wliich enters into the problem 

 of rendering visible minute details, but the aperture 

 of the objective forms another element. Working, 

 then, on tlie general lines laid down, lie had selected 

 as a set of powers, sufiicient for all the work of any 

 microscopist, the following: — 



One 4-incli objective of 0.10 n.a. = 12° an angle, nearly. 

 " 1 " " " 0.26 n.a. = 30° " " " 



" i " " " .94n.a. = 140° 



" i 1.42 n.a. 



" The first two to be dry-working objectives, with- 

 out cover-correction ; the tliird to be dry-working, with 

 cover-correction ; and the fourth to be a homogene- 

 ous immersion objective, with cover-correction; and 

 all to be of the higliest possible grade of workman- 

 ship. The stand should have a tube of such length 

 that standard distance of ten inches from the front 

 surface of objective to diaphragm of eye-piece can 

 be obtained on it, and to be furnished with six eye- 

 pieces; viz., 2-inch, 1-inch, and f-inch Huyghenian, 

 and |-inch, 5-inch, and ^-inch solid." 



In the evening the annual soiree took place, in con- 

 nection with the State microscopical society of Illi- 

 nois, at the Calumet club-house. There were two 

 hundred and fifty microscopes on the tables. A great 

 variety of objects were shown to a party of five hun- 

 dred guests of the club. 



There were a number of reports and papers to 

 be disposed of on Friday, the society adjourning at 

 five P.M. 



The first paper was by Dr. W. T. Belfield, on the 

 detection of adulteration in lard. Photographs rep- 

 resenting crystals of pure and adulterated lard were 

 exhibited. Those of the former are long, thin 

 plates, with beveled ends, while the crystals of tal- 

 low are plume-shaped, resembling somewhat an os- 

 trich feather. 



Dr. V. S. Clevinger presented a paper on the pa- 

 thology of the brain. 



Dr. Thomas Taylor's paper, on internal parasites in. 

 the domestic fowl, was read. The parasites referred 

 to were a mite from the lungs, another mite in the 

 cellular tissue, and an encysted nematoid from the 

 crop. 



A paper on the termination of the nerves in the kid- 

 neys was presented by M. L. Holbrook. The author's 

 method may be stated thus: "The fresh kidneys, 

 as well as those preserved in chromic-acid solutions, 

 were frozen in the freezing-microtome of Dr. Taylor, 

 and the sections allowed to remain in the gold so- 

 lution for varying periods of time, from forty min- 

 utes to several days. When removed, they were 

 carefully washed in distilled water, and placed in a 

 strong formic acid of a specific gravity of a hundred 

 and twenty degrees for from five to eight minutes, or 

 in a twenty-five-per-cent solution of the same for 

 hours and even days. Sometimes I obtained very good 

 specimens by placing the sections first in a dilute 

 twenty-five-ijer-cent solution of formic acid for twen- 

 ty-four hours, and afterward staining them with 

 chloride of gold until they reached the color desired. 

 . . . The nerves supplying the kidneys are mainly 

 of the non-meduUated variety. They accompany the 

 larger arteries of this organ, either in bundles, or in 

 flat, expanded layers; and the latter features I found 

 more common than the former. Sometimes an artery 

 would be found encircled by a network of non-me- 

 dullated nerves in a bewildering number. Hundreds 

 of such nucleated bundles of fibres could be traced 



