Ch. II] ' DESCENT OF MAN.' 47 



and otlior minor works. A 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 tho 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, 1840, I read Sir 

 C. Bell's admirable work on expression, and this greatly 

 increased tho interest which I felt in the subject, 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 domesticated 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 Hart- 

 field, whero 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 pro- 

 bable 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 nitrogenous and non-nitro- 

 genous 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 pursued 

 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 containing an acid and 

 ferment, closely analogous to the digestive fluid of an animal, 

 was certainly a remarkable discovery. 



During this autumn of 1876 I shall publish on the Effects 

 of Cross- and Self-Fertilisation in the Vegetable Kingdom. This 

 book will form a complement to that on the Fertilisation of 



