50 AUTOBIOGRAPHY. [ch. ii. 



second and largely corrected edition of the Descent appeared 

 in 1874. 



My book on the Expression of the Emotions in Men and 

 Animals was published in the autumn of 1872. I had 

 intended to give only a chapter on the subject in the Descent 

 of Man, but as soon as I began to put my notes together, I 

 saw that it would require a separate treatise. 



My first child was born on December 27th, 1839, and I 

 at once commenced to make notes on the first dawn of the 

 various expressions which he exhibited, for I felt convinced, 

 even at this early period, that the most complex and fine 

 shades of expression must all have had a gradual and 

 natural origin. During the summer of the following year, 

 1810, I read Sir C. Bell's admirable work on expression, and 

 this greatly increased the interest which I felt in the sub- 

 ject, though I could not at all agree with his belief that 

 various muscles had been specially created for the sake of 

 expression. From this time forward I occasionally attended 

 to the subject, both with respect to man and our domesti- 

 cated animals. My book sold largely ; 5267 copies having 

 been disposed of on the day of publication. 



In the summer of 1860 I was idling and resting near 

 Hartfield, where two species of [Sundew] abound ; and I 

 noticed that numerous insects had been entrapped by the 

 leaves. I carried home some plants, and on giving them 

 insects saw the movements of the tentacles, and this made 

 me think it probable that the insects were caught for some 

 special purpose. Fortunately a crucial test occurred to me, 

 that of placing a large number of leaves in various nitrcf- 

 genous and non-nitrogenous fluids of equal density ; and as 

 soon as I found that the former alone excited energetic 

 movements, it was obvious that here was a fine new field 

 for investigation. 



During subsequent years, whenever I had leisure I pur- 

 sued my experiments, and my book on Insectivorous Plants 

 was published in July 1875 that is sixteen years after my 

 first observations. The delay in this case, as with all my 

 other books, has been a great advantage to me ; for a man 

 after a long interval can criticise his own work, almost as 

 well as if it were that of another person. The fact that a 

 plant should secrete, when properly excited, a fluid con- 

 taining an acid and ferment, closely and analogous to the 

 digestive fluid of an animal, was certainly a remarkable 

 discovery. 



