200 



THE AMERICAN MONTHLY 



[Oct. 1881. 



But even under this amplification the 

 smallest bactina do not appear larger than 

 the points and commas of good print." 



We have not verified this calculation 

 and do not vouch for its accuracy. 



— We are indebted to M. Julien Deby, 

 for two pamphlets in which he treats of 

 the microscopical appearances of the 

 valves of diatoms, showing that " although 

 it is often difficult, at first sight, to interpret 

 the appearances presented by certain dia- 

 toms viewed as transparent objects under 

 the microscope, an attentive examination 

 of the details will, nevertheless, give the 

 interpretation of all the facts observed." 

 This he proceeds to demonstrate by means 

 of diagrams, illustrating Nitsschia and 

 Amphora in various positions. The 

 pamphlets are reprints from the Annales 

 de la Societi Beige dc Microscopie. 



— The Societe Zoologique de France 

 has published the report of a " Commis- 

 sion de nomenclature " appointed by the 

 Society to present a series of rules appli- 

 cable to the nomenclature of organisms. 

 The report is a most excellent one, and it 

 should be in the hands of every naturalist. 

 It was adopted by the Society, and the 

 rules for nomenclature have been briefly 

 summarized in the space of two and a 

 half pages, so that any person can easily 

 follow them. 



— Mr. C. M. Vorce has found that the 

 ground coffee sold in Cleveland, the greater 

 part of which is ground in that city, con- 

 tains a considerable proportion of starch, 

 which he was inclined to regard for a long 

 time as a mixture of pea and bean starch. 

 But further investigation, without the aid 

 of the microscope, has shown that only 

 peas are used there, in the sophistication 

 of the ground coffee, and these are bought 

 by the car-load. 



— The first part of the ■' Catalogue of 

 the Diatomaceae " is at last ready, and 

 will soon be in the hands of subscribers. 

 No one has regretted the delay in the 

 completion of this part more than we have 

 ourselves ; but the work is of a veiy diffi- 

 cult nature, and accuracy is only to be 

 attained in it by very close application and 

 extreme carefulness. We trust that sub- 

 scribers will show their appreciation of 

 the efforts we have made to put this valua- 

 ble work into a permanent form, by 

 promptly remitting the price, which, with 

 the number of subscribers we now have, 

 -will not quite pay the cost of publication. 



Exchanges. 



[Exchanges are inserted in this column without 

 charge. They will be strictly limited to mounted 

 objects, and material for mounting.] 



Wanted — First-class mounts of double-stain vege- 

 table preparations in exchange for first-class insect 

 preparati.ms. H. S. WOODMAN, 



P. O. Box 87, Brooklyn, E. D., N. Y 



Well-mounted Histological and Pathological slides 

 in exchange for other first-class slides. 

 W. H. Bates, M.D., 184 Remsen St. Brooklyn, N. Y. 



Wanted — first-class prepared and crude material, or 

 mounted objects, in exchange for diatoms in situ or 

 other first-class crude material, or for mounted objects. 

 M. A. BOOTH, Longmeadow, Mass. 



Wanted — Human Muscle with Trichina, in ex- 

 change for well-mounted slides of vegetable drugs. 

 OTTO A. WALL, M. D., 

 1027 St. Ange Ave., St. Louis, Mo. 



Niagara River Filterings for mounted slides. 



H. POOLE, Buffalo, N. Y. 



Wanted — good gatherings of Diatoms, fossil or re- 

 cent, especially of test forms. Liberal exchange in fine 

 slides ; prepared or rough material. Lists exchanged. 



C. L. PETICOLAS, 635 8th Street, Richmond,Va. 



Section of Braiu, stained, showing Tubercular Men- 

 ingites ; also Carcinoma Cerebri. Please send list. 

 L. BREWER HALL, M. D.,27 South i6th Street. 



Good, uncleaned Diatomaceous material containing 

 A rack noidiscus^ Heliopelta^ P/eiirosigyna^ Isthniia , 

 Triccratimii, Siirirclia gevtma and TerpsinocE 

 inusica wanted, in exchange for well-mounted slides 

 of arranged diatoms, etc., or cash. 



DANIEL G. FORT, Oswego, N. Y. 



Well-mounted Histological and Pathological slides, 

 in exchange for ax}n.e.x first-class slides. 



LEWIS M. EASTMAN, M. D., 

 349 Lexington Street, Baltimore, ]Md. 



For exchange : Mounted thin sections of whale- 

 bone, soapstone, serpentine, albite, feldspar, etc.; 

 also opaque mounts of several verj' beautiful fossil- 

 iferous limestones. 



Rev. E. A. PERRY, Quincy, Mass. 



Fine injected specimens of kidney', tongue and 

 liver, also very fine slides of human tooth, prepared 

 according to the method of Dr. Bodecker, showing 

 the protoplasmic net-work between the dentinal can- 

 aliculi, in exchange for first-class histological and 

 pathological slides, or other good specimens. 



J. L. WILLIAMS, North Vassalboro, Me. 



Well-mounted, tj'pical Pathological and injected 

 Histological preparations, in exchange for other well- 

 mounted slides, Diatoms, Algse and Fungi preferred. 

 HENRY FROEHLING, 

 59 N. Charles Street, Baltimore, Md. 



