286 PHYSIOLOGICAL BOTANY. 



oil. Castration has no further influence upon the irri- 

 tability, than that it lengthens the period of duration of 

 the flower, and thus of the pistil also. Experiment upon 

 the action of the pollen of the same flower ; this is only 

 exerted during the time of the susceptibility to impreg- 

 nation, but chemical irritants act at other times. In 

 many flowers, movement occurs during the period of im- 

 pregnation, without irritability; observations upon the 

 deportment of the flowers of Tropaolum majus, &c. 

 Observations upon Stylidium. 9. On the impregnation of 

 perfect plants. The dehiscence of the anthers in many 

 plants occurs uniformly before the flowers open, but in 

 most, afterwards. Action of light, heat, and moisture. 

 The author never succeeded in obtaining ripe seeds from 

 branches of dicotyledonous plants which were cut off and 

 kept in water. Other promoters of impregnation. Forty 

 grains of pollen were required to produce impregnation in 

 Malva Mauritiana. Similar experiments upon Tropceo- 

 lum majus. Precautionary rules and phenomena of arti- 

 ficial impregnation. The nucleus is capable of continuing 

 its growth for some time without impregnation, but it 

 does not produce an embryo. Phenomena observed after' 

 fructification in the nucleus and the seeds of twelve 

 flowers of Lychnis vespertina. Similar observations upon 

 Staphylcsa pinnata, during a period of four months ; in 

 both cases with accurate anatomical investigations, but 

 without figures. He arranges my observations upon 

 Angraecum with his own upon the embryo of Corydalis, 

 but he is still unacquainted with the figures in my 

 Anatomico-Botanical Plates, which would have taught him 

 the great difference between them. 10. Upon the abor- 

 tion of flowers, fruits, and seeds. Shorter than the other 

 memoirs. 11. Upon the production of fruits, with seeds 

 capable of germination, without the application of pollen. 

 The observations of others upon the subject are criticised, 

 and their insufficiency pointed out. His own observations 

 yielded a perfectly negative result. 12. On the impreg- 

 nating power of plants. 13. On false impregnation. 



