1C8 LIFE OF 



This secretion, when excited by nutritious matter, 

 becomes distinctly acid, and contains a digestive ferment 

 allied to the pepsin of the human stomach. So excited, 

 it is found capable of dissolving boiled white of egg, 

 muscle, fibrin, cartilage, gelatine, curd of milk, and many 

 other substances. Further, various substances that 

 animal gastric juice is unable to digest are not acted upon 

 by the secretion of the sun-dew. These include all 

 horny matter, starch, fat, and oil. It is not however 

 prejudiced in favour of animal matter. The sun-dew can 

 absorb nutriment from living seeds of plants, injuring or 

 killing them, of course, in the process, while pollen and 

 fresh green leaves yield to its influence. 



The action of salts of ammonia and other chemicals 

 was even more wonderful. " It is an astonishing fact 

 that so inconceivably minute a quantity as the one twenty- 

 millionth of a grain of phosphate of ammonia should 

 induce some change in a gland of Drosera sufficient to 

 cause a motor impulse to be sent down the whole length 

 of the tentacle ; this impulse exciting movement often 

 through an angle of above 180. I know not whether 

 to be most astonished at this fact, or that the pressure of 

 a minute bit of hair, weighing only ^y^nr f a grain* 

 and largely supported by the dense secretion, should 

 quickly cause conspicuous movement." 



These are but specimens of a multitude of profoundly 

 interesting facts brought out in this exhaustive investiga- 

 tion. If this single research were his only title to fame 

 Darwin's name must rank high as an experimenter of rare 

 ingenuity and success. But he concludes his summary 

 of results by the utterly modest remark, " We see how 



