12 PLANT HYBRIDIZATION BEFORE MENDEL 



date was practised solely for the production of the fruit and not 

 for the production of seeds or for the purpose of breeding the 

 plant. The breeding of new plants remained a mere matter of 

 chance and was due to the selection of superior bearing trees 

 where they occurred. It is otherwise possible that, if annual 

 grain-plants of the dioecious type had been accessible, further 

 advance might have been made in plant breeding, even at an 

 early period. As a matter of fact however, no lesson was learned 

 from the example of the date palm. The book was closed — and 

 the land of Babylonia, where those whom we may call the first 

 plant breeders lived, became the desert which it remains to this 

 day. Literally, in the words of the Prophet Jeremiah, "Her cities 

 are a desolation, a dry land, and a wilderness." 



6. The First European Investigations on Plant Sex. Camerarius 

 (1665-1721). 



On the 25th of August, 1694, Rudolph Jakob Camerer, Pro- 

 fessor of Natural Philosophy in the University of Tubingen, bet- 

 ter known under the Latinized name of Camerarius, published a 

 memoir in the form of a letter to a colleague. Professor Michael 

 Bernard Valentin, of the University of Giessen. 



This extraordinary "letter" is entitled "De Sexu Plantarum 

 Epistola" (2). It recounts at length the knowledge, slender enough 

 though it was, on the subject which existed up to his time, gives 

 a description of Camerarius' own experimental work, and consti- 

 tutes the first contribution in the form of an actual scientific in- 

 vestigation into the question of the existence of sex in plants. 



The Greek and Roman writers on natural history, Aristotle (1), 

 Herodotus (5), Pliny (11), Theophrastus (15), and others, had 

 commented on the supposed existence of the sexes in plants, even 

 definitely citing the case of the date palm ; but the texts report 

 no actual experiments for determining the facts. This latter, 

 therefore, was the contribution of Camerarius. 



Camerarius appears to have been the first botanist to discover, 

 by actual experimentation, that the pollen is indispensable to 

 fertilization, and that the pollen-producing flowers or plants are 

 therefore male, and the seed-bearing plants female. The experi- 

 ments were conducted with Mercurialis, spinach, and hemp, all 

 of which are dioecious, and with Indian corn or maize. Camer- 

 arius was likewise the first investigator to discover, in the case 



