566 



POPULAR SCIENCE MONTHLY. 



same in an English dress (London, 

 1900), also the 'Letters of Schonbein 

 and Liebig, 1853-1869 ' (Leipzig, 1898), 

 so that the correspondence of Schon- 

 bein is largely accessible to students 

 seeking details. 



These several volumes of correspond- 

 ence suggest others that are analogous. 

 The ' Letters of Berzelius and Liebig, 

 1831 to 1845,' edited by Justus Carrifere 

 with the cooperation of the Bavarian 

 Academy of Sciences (Munich, 1893), 

 and the correspondence between Berzel- 

 ius and Wohler, published by the Royal 

 Academy of Gottingen, and edited by 

 0. Wallach (Leipzig, 1901, 2 vols.). 



And to complete this series of letters 

 that passed between eminent chemists 

 there remains the ' Correspondence of 

 Liebig and Wohler,' edited by A. W. von 

 Hofmann, and Emilie Wohler (Braun- 

 schweig, 1888, 2 vols). These cover 

 the long period from 1829 to 1883. The 

 inter-relations of these six works with 

 the dates of the correspondence and of 

 the death of each chemist, may be 

 graphically shown by a diagram. 



t 

 ft 





1 !SSZ 



The perusal of letters between inti- 

 mate friends having mutual interests 

 in kindred studies is much like listen- 

 ing to conversation carried on between 

 them; they reveal their daily life, 

 domestic happiness and difficulties. 



their likes and dislikes, their humor 

 and their satire, their successes and 

 failures in research, and their ambi- 

 tions and discouragements. They also 

 disclose their weaknesses and perhaps 

 their foibles, and they unconsciously 

 divulge the greatness of their intellects, 

 all in simple language, not written to 

 produce startling effects nor to ex- 

 aggerate their own importance in the 

 minds of readers. 



All these volumes are illustrated by 

 one or more portraits, and some of 

 them contain facsimiles of manuscripts. 



MOSQUITOES. 

 A Monograph of the ' Culicidse or 

 Mosquitoes of the World ' has just been 

 prepared by Mr. Fred. V. Theobald, 

 and is published by the British Museum 

 as one of its regular series. There are 

 two volumes of text aggregating 835 

 pages and one volume of plates, num- 

 bering 37 and containing 148 colored 

 figures of adults. Then there are 5 

 plates, each containing six solar prints 

 of microphotographs illustrating wing 

 scales. In the text are 318 woodcuts, 

 half-tones or similar figures. In these 

 books 258 species of mosquitoes, divided 

 among 22 genera, are described, and 37 

 species in 10 genera are credited to 

 North America. Although the work 

 is just off the press it is already out of 

 date, and in the introductory remarks 

 by the director of the musevim, dated No- 

 vember, 1901, a supplementary volume 

 is promised. All these facts indicate 

 the remarkable interest that has been 

 of late universally aroused in the sub- 

 ject, and the enormous collections that 

 have been and are now being made in 

 all parts of the world. In the United 

 States several new species were recog- 

 nized and described in 1901, two of 

 them from New Jersey. The life his- 

 tory of several species has been made 

 out, and good structural characters for 

 their separation appear as the result of 

 American study. Mr. Theobald de- 

 scribes 136 new species; almost as 

 many as were described in all previous 



