HOW PLANTS USE ANIMALS.* 



By Prof. James Fowler, Ph. D. 



|ITROGEN enters into the composition of proteid substances 

 and is consequently a necessary element of plant- food. 

 Experiments have proved that it is derived, not from the 

 nitrogen of tlie air, but from compounds of ammonia and nit- 

 rates which are widely distributed in nature, and are furnished 

 to the plant dissolved in soil-water. Plants, with few excep- 

 tions, have no power to assimilate the free nitogen of the atmo- 

 sphere, and soon perish if the coil in which they grow contains 

 no nitrogen compounds. When growing in positions where the 

 necessary nitrogen cannot be obtained they are compelled to re- 

 sort to other sources of supply. Some secure abundance for their 

 needs from the bodies of animals which they entrap in various 

 ways, and as the greater number of these are insects the plants 

 have been called insectivorous plants. 



About 460 plants are known which are more or less depend- 

 ent upon this source for their nitrogen, and are consequently 

 provided with traps, pitfalls antl other contrivances for captur- 

 ing their prey. They belong to diflerent families or orders of 

 both terrestrial and aquatic forms, and are furnished with wide- 

 ly different devices tor securing the animals required for food. 



Order T. — Among these insectivorous plants the most con- 

 spicuous belong to the order Sarraceniaceae, wl.ich embraces 

 eight species, distributed between three genera, inhabiting North 

 America and British Guiana. 



I. The best known of these are: 



The six species of pitcher plants (Sarracenia), of which one 

 (S. purpurea) is common in Canada, and ihe other five in the 

 Southern States. They abound in mossy bogs, and along the 

 borders of lakes. They are perennial plants, with stems from a 

 foot to eighteen inches in height, terminated by a single, large, 

 nodding flower, of a deep purple or sometimes greenish-pnrplo 



* Republished by permisskm of Quet-n's Quart t-i-ly. 1«'.W. 



