852 



THE POPULAR SCIENCE MONTHLY. 



attention that so remarkable an instrument 

 deserves. The staining and injecting of ob- 

 jects are as fully treated of as the size of the 

 book would permit, and a colored frontis- 

 piece is introduced to show the effect of 

 double-staining on wood-sections. 



The author exhibits commendable fair- 

 ness in his treatment of American micro- 

 scopists, and of instruments made on this 

 side of the water, especially the wide- 

 angled objectives of Spencer, of Geneva, 

 and Tolles, of Boston. Ue says : " It is 

 only recently that American objectives of 

 the widest aperture have found their way 

 into the author's hands. Their definition 

 is marvelous." Medium angles have been 

 advised for students' use, because they can 

 be employed without much previous knowl- 

 edge or difficulty ; but for all purposes of 

 scientific investigation wide apertures give 

 more satisfactory results. 



Many of the illustrations have been 

 photographed by the author from nature 

 and then cut in wood. Some of these are 

 very fine, as, for example, the sting and 

 poison-bag of the bee and wasp, the diges- 

 tive apparatus of the water-beetle and of 

 the blow-fly, and various other natural ob- 

 jects. 



The rapid strides that have recently been 

 made in the manufacture of cheap and very 

 good working microscopes have created a de- 

 mand for works of this character, and Mr. 

 Davis's book supplies a real want. 



Guide to the Flora of Washington and 

 Vicinity. By Lester F. Ward, A. M. 

 Washington : Government Printing-Of- 

 fice. 1881. Pp. 264. 

 This recent publication of the Smith- 

 sonian Institution contains the scientific and 

 common names of 1,384 plants found in the 

 vicinity of the national capital, together 

 with their time of flowering, and in many 

 cases the localities where they may be 

 sought for. Appended arc a check-list and 

 a map of the region for fifteen or twenty 

 miles around the city of Washington. The 

 labor of preparing a " flora " of even a lim- 

 ited space of country is much greater than 

 might be supposed, and in the present case 

 many able and active botanists have co- 

 operated with the author, as well as many 

 energetic amateurs. The appearance of this 

 work recalls to mind a remark of the late 



Dr. John Torrcy, that in his younger days 

 he attempted to prepare a flora of the City 

 Hall Park, New York. At that time there 

 was neither post-office nor court-house 

 there. Even in that small space he met 

 with so many and such a rapidly increasing 

 number of varieties and species that he was 

 compelled to abandon the project. From 

 its cosmopolitan nature New York naturally 

 receives fresh additions to her flora annual- 

 ly from every quarter of the globe. Even in 

 Washington there has been a considerable 

 change in the flora since the " Prodromus " 

 appeared half a century ago. Of the 860 

 distinct plants enumerated therein, the au- 

 thor has succeeded in identifying 70S, while 

 nearly as many more have been added. 

 Although the primary aim of the author 

 was to furnish a guide to botanists in ex- 

 ploring the locality, it will serve as an aid 

 to beginners in practical botany elsewhere. 

 An appendix is added, especially addressed 

 to the latter class, and containing among 

 other things suggestions regarding identi- 

 fication of plants, collection of plants, pres- 

 ervation of plants, making an herbarium, 

 care of duplicates, exchanging specimens, etc. 

 On the first of these points the author re- 

 marks that " a young botanist's struggles 

 with botanical keys can only be sympa- 

 thized with ; they can scarely be aided by 

 any general directions, and there is no more 

 effectual drill than the persevering effort 

 to identify, by the aid of a key, a plant to 

 which he has no clew. It should be the 

 ambition of every such beginner to analyze 

 in this manner all the plants of his local 

 flora." The less help he receives the better, 

 and, the more ignorant the beginner is at 

 the outset, the better will be his ultimate 

 acquaintance with botany if he perseveres 

 in the work. In regard to localities the 

 writer very appropriately remarks that " in 

 many respects the botanist looks at the 

 world from a point of view precisely the 

 reverse of that of other people. Rich fields 

 of corn are to him waste lands ; cities are 

 his abhorrence, and great open areas under 

 high cultivation he calls 'poor country'; 

 while on the other hand the impenetrable 

 forest delights his gaze, the rocky cliff 

 charms him, thin-soiled barrens, boggy fens, 

 and irreclaimable swamps and morasses are 

 for him the finest land in the State. He 



