LIFE IN THE TROPICS 465 



likewise support a series of small creatures ; so also 

 the epiphytic orchids and Tillandsias. Thus a single 

 tree, with its accompanying smaller plants, supports 

 a great population of insects, snails, centipedes, etc. 

 When the trees are so varied, jt will readily be under- 

 stood that the fauna must be enormous. A Colorado 

 high school teacher, a few years ago, secured a leave of 

 absence from her school to visit Guatemala. She was 

 away six weeks, two of which were occupied by the 

 journeys, coming and going. In the month she had 

 in the country she was able to discover 78 species and 

 varieties new to science, including a large and beautiful 

 tree, a snail, several protozoa, and a great number of 

 insects. 



4. One might suppose that the study of tropical Tropical 

 life, owing to its variety and complexity, would be usuaUy 

 extremely difficult. It is anything but easy, but the defined 

 naturalist who has struggled with the poorly defined 

 species of temperate regions turns with relief to the 

 tropical biota, where the different forms commonly 

 possess recognizable or even conspicuous characteris- 

 tics. In the tropics it appears that conditions must 

 have remained substantially the same during long ages, 

 while the intense struggle for existence has hewed, 

 as it were, each species very closely to the line of 

 optimum efficiency. Thus characters have become 

 stereotyped, species fit exactly into their niche in the 

 architecture of nature, and general variability is likely 

 to be suppressed. In temperate regions we are re- 

 covering from the last glacial period, species are still 

 plastic and in the making, at least in many genera, and 

 it is difficult to define them exactly, for the reason that 

 Nature has not done it. In large collections from the 

 tropics, for example of wild bees, it often appears that 



