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An example of the fact that the more or less free situation in 

 fluences the number of perforations of the flowers is found in two 

 species of the genus Faradaya, both having nectaries on the caljx 

 and the leaves. With Faradaya iKipuana Scheff., which stands in 

 the Botanical Garden at Buitenzorg surrounded by many other richly 

 flowering plants, the flowers are often perforated by a boring wasp ; 

 of the fallen flowers only 1 7o was undamaged. This was different 

 with another still unnamed species of the same genus which, as far 

 as the nectaries were concerned, showed no difference with the 

 former and grew at some distance from it in a less open site. Its 

 branches hung partly to the ground and bore far fewer flowers 

 than Faradaya papuana. Now of this three 19,3 7o of the flowers 

 remained unperforated. 



And in regard to the weather it appeared that the number of 

 bored flowers closely depends on it. After a sunny day a much 

 larger number of flowers had been bored the next morning than 

 when rain had prevented the insects from flying out. This was 

 e. g. very conspicuous with Ipomoea carnea Jacq., a shrub having 

 nectaries as well on the leaves as on the calyx, the latter being 

 bored by Vespa analls and two Xylocopas. Collected in the morning 

 without regard to the weather of the preceding day 907o of the 

 fallen flowers were bored; after rainy days 57 7o of the flowers 

 were damaged and after sunny days even 99,1 7o were bored. 



From this appears most clearly how little value must be assigned 

 to statistical data about the perforation of flowers and about their 

 being eventually protected by ants if not at the same time all other 

 circumstances which may influence the results have been taken into 

 account. 



When trying to fix the part, either favourable or otherwise, played 

 by insects with regard to a plant, one meets with greater difficulties 

 in the tropics than e.g. in Middle Europe, because the vegetative period 

 lasts so much longer. So one may meet an abundance of definite 

 insects during one part of that period which are not found during 

 another part. This special difficulty of the question whether special 

 arrangements in a plant form an adaptation to a definite animal 

 species is still enhanced in a botanical garden by the circumstance 

 that there nearly all the plants are in a more or less uncommon 

 site or surroundings. Yet here also the mutual behaviour of the animals 

 frequenting the plants may be investigated as well as their behaviour 

 towards the plants themselves, while the results enable us to draw 

 some justified conclusion as to the mutual relations in the natural 

 sites of these plants. I took this point of view when I began my 



