CH. XLII. BIOLOGY. . 473 



fluid, and Dr. Curtis, in 1834, showed that this fluid acts 

 like the gastric juice of an animal in digesting and dissolv- 

 ing the animal matter. Since then Mr. Darwin's work on 

 ' Insectivorous Plants' (1875) and Dr. Burdon Sanderson's 

 experiments have dealt with the whole subject. It seems 

 that even the lightest gnat resting on the glands of the 

 leaves of one of these species excites the minute hairs 

 with which they are covered and causes the leaf to close, 

 and Dr. Sanderson has shown that the same kind of elec- 

 trical current is set up in the leaf by this movement, as 

 occurs in our own muscles when they contract. The 

 glands of the leaf next begin to pour out a sticky fluid, 

 which dissolves the substances of the insect in just the 

 same proportions and in the same manner as the gastric 

 juice of our stomach dissolves the substances in our food ; 

 and lastly, when the leaf unfolds, and the tentacles or little 

 hairs rise up again, letting the refuse of the dead insect 

 drop, the glands cease to give out the fluid until another 

 insect is caught and the process begins again. The whole 

 history of these carnivorous plants, though they are excep- 

 tional in the vegetable kingdom, is one of the most interest- 

 ing that can be imagined, and forms another unexpected 

 link between the nature of plants and animals, while at the 

 same time we have no new organs created, but only modifi- 

 cations of those common to plant life. 



Lastly, the mere collector of plants has quite a new 

 interest in his work, for it is no longer an ultimate fact that 

 any particular plant inhabits such or such a country. We 

 have now to learn how it came there, to trace out its near 

 K Nations in other countries, and to track its line of migra- 

 tion, just as we do that of a race of people ; explaining the 

 modifications it has undergone by the length of time it has 

 been living under new conditions, separated perhaps b> a 



