117 

 The same fact holds true in Trifolium pratenne when grow- 

 ing in fields, and Phaseolus multiflorus when grown in 

 large and conspicuous clusters in gardens. It is a well- 

 known fact that alpine flowers grow in much larger masses 

 than plants of lower regions. Familiar examples of our 

 flora are afforded by Silene acaulis, Arenaria, Groelan- 

 dica, Bryanthus taxifolius, Trifolium sp., Ledum, etc. 

 Mueller has shown of alpine and'subalpine plants that more 

 were visited in the Alps than in the lowlands and also that 

 more species were perforated as is well shown by the list of 

 flowers which Bombus mastrucatus visits. 



Flowers grown in large masses are conspicuous, and 

 therefore attract many insects ; and, as the perforated flowers 

 usually contain considerable nectar, the number of insects 

 visiting the flowers at any one time is very large, and, as 

 Darwin has shown, some of the nectaries are sucked dry; 

 now, in order to save time, for the flowers would have to be 

 probed for their nectar, the insect makes peiforations. To 

 this rule there are exceptions, as has been shown in some of 

 the cases cited, where an insect, unable to get a nectar in a 

 normal way, takes to perforating flowers. Mueller and 

 others have shown that there is a certain correlation between 

 the length of the tongues of Hymenoptera and the flowers 

 they perforate, as can be seen by consulting their tables on 

 Showers and their visitoi's. 

 -^v^JimJO Flowers are Protected. We have briefly called 

 attention to a few of the agents which destroy flowers. It is 

 equally interesting to study the contrivances which protect 

 the flowers from unbidden guests. Darwin has well said in 

 a prefatory letter to Dr. Wm. Ogle's translation of Kerner's 

 admirable book on "flowers and their unbidden guests:" 

 "The beauty and poefeBy of flowers will not be at all lessened 



