78 The Science of Life. 



The custom of dusting the female date-palm with the 

 pollen from the male flowers, and the more complicated 

 process of caprification in the case of fig- 

 jtcSres fsto trees, were doubtless quite empirical at first. 

 p?an5? ity f ^ v anc * ky they seem to have been dimly un- 

 derstood by a few, as may be interred from 

 Pliny's description of pollen as the material of fertiliza- 

 tion, or from the verses of Ovid; but there was little 

 more than confused conjecture until the seventeenth 

 century. A few experiments would have settled the 

 question, but the day of experiment had not yet dawned. 

 Rudolph Jacob Camerarius (1665-1721), professor at 

 Tubingen, showed experimentally (1691-1694) that seeds 

 Camerarius ca P aD ^ e f germination cannot be formed 

 without the co-operation of pollen. His first 

 observations were on the mulberry and the dog's mer- 

 cury (both dioecious, i.e. with separate sexes), and he 

 soon extended his experiments to other plants. He 

 called the anthers the male sexual organs, and the 

 ovaries the female sexual organs, and insisted that 

 these terms were not to be taken figuratively. This 

 would be held as rather rough-and-ready terminology 

 nowadays, but at the time Camerarius was justified in 

 his insistence. 



Joseph Gottlieb Kcelreuter (1733-1806), professor of 

 natural history at Carlsruhe, may be said to link 

 Kcelreuter Camerarius with such modern workers as 

 Nageli. Indeed, as Sachs says, " his works 

 seem to belong to our own time; they contain the best 

 knowledge which we possess on the question of sexu- 

 ality". "He made the first careful study of the dif- 

 ferent arrangements inside the flower in their connection 

 with the sexual relation, discovered the purpose of the 

 nectar and the co-operation of insects in pollination, and 

 proposed that view of the sexual act which, with some 

 considerable modification, we must still in the main 

 consider to be the true one, namely, that it is a min- 

 gling together of two different substances." He is best 

 known by his extensive and fundamental experiments 

 on hybridization in plants, experiments which should 

 have exerted an even greater influence than they have 



