ZOOLOaT AND BOTANY, MICROSCOPY, ETC. 625 



After dealing with the individual peculiarities of 422 specimens 

 of phanerogams (the descriptions being supplemented by many excel- 

 lent figures), and enumerating the insects found on each, the author 

 considers at length the significance of these peculiarities ; discusses 

 the adaptations of flowers to insect visits, and the extent of these 

 visits ; the adaptations of insects for floral activity, and the varia- 

 bility of Alpine flowers ; and makes an extended comparison of 

 Alpine flowers with those of the lowland. 



As was to be expected, the author finds that everywhere, even to 

 the limit of phanerogamic life — the line of perpetual snow — the rule 

 holds that cross-fertilization, constant or occasional, is provided for 

 in every species, so that not a single flowering plant is known which 

 is incapable of being crossed at some time. A series — from the 

 simplest anemophilous flower, whose only attraction to insects lies in 

 its pollen, to the most highly adapted bee or butterfly flower, with 

 fragrance, attractive form and coloration, and nectar — is fully traced 

 and illustrated by many examples. A valuable feature of the work 

 is the large number of comparative tables, which enable the reader to 

 see at a glance relations which, without this aid, would require much 

 study for their detection. These show very clearly that as flowers 

 ascend in the scale of development, their visitors, though often 

 decreasing in actual number of species, become limited more and 

 more to certain groups whose floral activity is great, and from whose 

 visits they receive the greatest profit. In spite of the frequently 

 recorded scarcity of insects at high altitudes, under some conditions, 

 the author says, " I have not been able to convince myself that, in 

 the Alps, flowers as a whole are relatively less visited and crossed 

 by insects than in the lowland." This results partly from the con- 

 solidation of vegetation into veritable flower-gardens, a circumstance 

 very favourable to insect visits anywhere ; and it is found that while 

 in the pleasantest weather a moderately cool breeze suffices to di'ive 

 the insects quickly under shelter, a quiet, sunny day, coming suddenly 

 after several cold and rainy ones, brings them out in great abundance, 

 their enforced concealment and fast having whetted their appetites 

 and rendered them exceedingly active in their visits to the flowers. 

 This is strikingly illustrated by the fact that 1877, which was cold, 

 damp, and rainy, but with occasional quiet, warm days, was not less 

 productive of observations than the preceding summer, when for 

 weeks together there was scarcely a cloud overhead. So while one 

 day there may not be an insect visible, the next may witness them in 

 great abundance. 



From a table showing the abundance and activity of the different 

 orders of insects, it appears that in ascending the mountains the 

 relative number of Coleoj)tera and Hymenoptera decreases, while that 

 of Diptera and Lepidoptera increases. Thus, in the lowlands, of 

 every 100 flower- visiting insects, 15*3 are Coleoptera and 30 Diptera, 

 while 43 • 6 are Hymenoptera, and but 9 • 3 Lepidoptera ; but above 

 the timber line, with 6 • 8 per cent, of Coleoptera, we have 43 • 6 per 

 cent, of Diptera, and with 18 "3 per cent, of Hymenoptera, 30*7 

 per cent, of Lepidoptera. This renders intelligible the great abun- 



