224 THE NATURALIST IN NICARAGUA. [Ch. XII. 



noticed them first in Northern Brazil, in the province of 

 Maranham ; and afterwards at Para. Every pouch was 

 occupied by a nest of small black ants ; and if the leaf 

 was shaken ever so little, they would rush out and scour 

 all over it in search of the aggressor. I must have tested 

 some hundreds of leaves, and never shook one without 

 the ants coming out, excepting one sickly-looking plant 

 at Para. In many of the pouches I noticed the eggs 

 and young ants, and in some I saw a few dark-coloured 

 coccidse or aphides ; but my attention had not been at 

 that time directed to the latter as supplying the ants 

 with food, and I did not examine a sufficient number of 

 pouches to determine whether they were constant occu- 

 pants of the nests or not ; but my experience since with 

 the cecropia trees would lead me to expect that they 

 were. If so, we have an instance of two insects and a 

 plant living together, and all benefited by the com- 

 panionship. The leaves of the plant are guarded by the 

 ants ; the ants are provided with houses by the plant, 

 and food by the coccidee or aphides ; and the latter are 

 effectually protected by the ants in their common habi- 

 tation. 



Amongst the numerous plants that do not provide 

 houses, but attract ants to their leaves and flower-buds 

 by means of glands secreting a honey-like liquid, are 

 many epiphytal orchids, and I think all the species of 

 Passrflora. I had the common red passion-flower grow- 

 ing over the front of my verandah, where it was con- 

 tinually under my notice. It had honey- secreting glands 

 on its young leaves and on the sepals of the flower-buds. 

 For two years I noticed that the glands were constantly 

 attended by a small ant (Pheidole), and, night and day, 



