160 



THE AMERICAN MONTHLY. 



[August. 



correspondent somewhat by saying that 

 in the first edition of Tuckett's ' Trea- 

 tise,' (1848,) p. 438, he refers to Navi- 

 cula Hippocampits as resolved by Robert 

 Harrison in 1841, but making no mention 

 of Spencer in connection with that form. 

 He, however, devotes some space (p. 440) 

 to N. Spejicerii, which had that year, 1848, 

 been brought to the attention of English 

 microscopists by Prof. Bailey, of West 

 Point, who stated that a young back- 

 woods artist named Spencer had, with 

 an object-glass of his own construction, 

 shown three sets of lines on this diatom, 

 while objectives of equal power by the 

 first English opticians had failed in de- 

 fining them. 



Two English observers had later, how- 

 ever, made out the markings clearly and 

 resolved them into 'dots,' and one of 

 them, Mr. De La Rue, furnished Ouekett 

 with a plate delineating this diatom under 

 800 and 1900 diameters. This plate is 

 numbered ix in the first edition of the 

 Treatise. But in the third edition (1855) 

 both the plate and the article on N. Spen- 

 ccrii are wholly omitted, and no allusion 

 whatever made to them. This omission 

 is significant, as the paragraph on A'. 

 Hippocavipns and other test diatoms are 

 repeated verbatim. 



As I have not the second edition (1852) 



of Tuckett's Treatise, I am unable to state 



whether it contained the article referring to 



Mr. Spencer, nor the cause of its omission. 



Yours truly, 



J. P. Thompson. 

 Portland, Me., July 20, 1886. 



[The book referred to in the above let- 

 ter, we are sorry to say, could not be found 

 in Washington. — Ed.] 



NOTICES OF BOOKS. 



Disinfection and Ittdividiial Prophylaxis 

 against Infectious Diseases. By George 

 M. Sternberg, M. D., Major and Sur- 

 geon, U. S. A. Concord, N. H.: Repub- 

 lican Press Association, 1886. (Pam- 

 phlet, 8vo, pp. 40.) 



This is the Lomb prize essay of the 

 American Public Health Association. 

 More than one-half of the essay relates 

 to the important subject of disinfection, 

 which is treated in a masterly manner. 

 An excellent solution is recommended, 

 composed of mercuric chloride, 4 ounces ; 

 copper sulphate, i pound ; water, one gal- 

 lon, to be used in the proportion of i to 100 

 parts for the destruction of spores. 



The second part treats of individual 

 prophylaxis, and contains much sound 



and reasonable advice to those brought 

 in contact with infectious diseases, or who 

 reside in unhealthful localities. 



The Public Health Association has done 

 well to publish such a useful pamphlet, and 

 to Mr. Henry Lomb, of Rochester, the pub- 

 lic is deeply indebted for giving such lib- 

 eral encouragement to the preparation of 

 it. The prize awarded was $500.00, and 

 we think it justly won. 



Fur Fibres as shown by the Microscope. 



By Henry L. Brevoort. 1886. (Quarto. 



pp. 3, plates 16. 



The author of this work, which is almost 

 entirely made up of plates drawn accu- 

 rately to scale, has been engaged for a 

 long time in studying fur fibres. The 

 explanatory text is very brief, but the 

 plates are undoubtedly accurate. From 

 his studies of fur the author has drawn 

 some conclusions of importance in the 

 business of manufacturing, which have 

 not been made public ; but one point he 

 brings prominently forward, the preva- 

 lence of the air cells and the almost 

 entire absence of pigment from the fur 

 of animals that have to resist dry cold, 

 the air-cells being such excellent insu- 

 lators, and no space can be spared for 

 pigment. On the other hand, in the case 

 of animals living in a moist climate, the 

 pigment cells are present, since they make 

 the fibre more repellent to water. 

 .Medical ajid Surgical Directory of the 



United States.^ R. L. Polk & Co., 



Publishers, Tribune Building, Detroit, 



Mich. 



The urgent necessity of such a work had 

 long been apparent to the medical profes- 

 sion. In the present laborious undertak- 

 ing, we are glad to see, the publishers have 

 spared no pains to make the book what it 

 ought to be, a reliable and official list of 

 all legally-recognized practitioners within 

 the limits of the LInited States and Terri- 

 tories. Their names, 80,000 in number, 

 are accompanied by all the attainable 

 information regarding place and time of 

 graduation, and the arrangement adopted 

 by the publishers could scarcely be im- 

 proved upon. The work cannot fail to 

 be appreciated by the profession. 



Exchanges. 



[Exchanges are inserted in this column without 

 charge. They will be strictly limited to mounted ob- 

 jects, and material for mounting.] 



For Exchange : Seeds ot Orthocarpus purpurascens 

 and Orthocarpus attenuatus , and slides of same, in ex- 

 change for good objects, foraminifera preferred. 



EDWARD GRAY, M. D , 

 Benicia, Cal. 



