( i51 ) 



thick and darker eolourcMi points. On the inflorescences two kinds 

 of ants always abound, one large and one small species. Even when 

 the flower-buds are still closed the ants are already found on the 

 bracts and no sooner are the flowers open than the ants also attack 

 the perianth leaves. It appeared that sugar was secreted as a bait here. 



In order to prove this the flowers were placed for some time 

 under a damp glass bell-jar; after a few hours by means of Feeling's 

 reagent sugar could be proved to be present in the liquid secreted 

 by the leaves at the exterior side. I could find no special organs 

 for this secretion, however; probably the secretion is an internal one 

 the product being brought out by the epiderm or the stomata. 



It was already known to Delpino that some orchids secrete sugar 

 on the perianth; the remarkable point with the just mentioned 

 Spathoglottis is that the ants have such an injurious influence on it. 

 Whereas namely the small s[)ecies remains on the flowers and is 

 content with the sugar there secreted, the big species also descends 

 to the basal-leaves and attacks these also, often to such an extent 

 that only a skeleton of them remains. These harmful big ants are 

 not expelled at all by the much more numerous small ones. It 

 further appeared most clearly that the secretion of sugar was the 

 reason indeed why such important organs as the leaves were eaten 

 by the big species. The proof was namely afforded by those plants 

 that had finished flowering and bore fruit: with these secretion of 

 sugar took place no louLier arnl the leaves, wdiich were produced in 

 this period, remained consequently ujiinjured. So it was the secretion 

 of sugar during the flowering period which attracted the ants, while 

 the leaves as such were no sufficient bait. 



A second instance of the great harm that may be caused to the 

 plants themselves by the secretion of sugar, is seen with various 

 tree- and shrublike Malvaceae. In the Botanical Garden stands an 

 uimamed tree, a Malvacea from Indo-China. This not only has 

 nectaries on the leaves and calyx, but also offers the ants a very 

 suitable dwelling-place in the stipules, which occur in pairs and are 

 bent towards each otlier. The spaces formed in this way are indeed 

 inhabited by ants, but not by so many as might be expected. The 

 reason is that in spite of the abundance of nectaries they find no 

 sufficient food, since on these trees a species of bugs occurs which 

 not only consume the secreted sugar but also eat the nectaries them- 

 selves. These bugs moreover injure the leaves to such an extent 

 that the tree suffers from it, as may be seen by a cursory examina- 

 tion. The same may be stated of a tree named ''Malvacea Karato" 

 and of some other species of this family. 



11* 



