104 



The Journal of Heredity 



The reason for their faiUire to do so is, 

 however, in a measure explainable. No 

 other important plants with which they 

 came into contact in their fields ex- 

 hibited a similar striking division into 

 two distinct sexes. For example, they 

 did not chance to possess at the same 

 time a plant like Indian corn, in which 

 the sexes are at least partially sepa- 

 rated, in which pollination is a conspic- 

 uous fact, and in which crossing not 

 only can be seen to be continually tak- 

 ing place in nature but can likewise 

 easily be carried out by artificial meth- 

 ods. Otherwise it is possible that a 

 further advance would have been made 

 in plant breeding, even in those early 

 times. As a matter of fact, no second 

 lesson was learned. The book was 

 closed, and the land of Babylonia, where 

 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." 



BEGINNING OF THE NEW LESSON 



Ages of oblivion had rolled over the 

 land where nature taught men their 

 first lesson in plant breeding. Nearly 

 all that we commonly call the history 

 of the world had taken place. On the 

 25th of August. 1694, in his laboratory 

 in the University Tubingen, in South 

 Germany, Rudolph Jacob Camerer, 

 Professor of Natural Philosophy, bet- 

 ter known to science under his latinized 

 name of Camerarius, finished the writ- 

 ing of an extremely long letter to his 

 friend, Professor Michael Bernhard 

 Valentin, of the University of Giessen. 

 This extraordinary "letter," which fills 

 some fifty printed pages, is entitled 

 "De Scxn Plaiitantm Epistola."'^ It 

 recounts at length, not only the knowl- 

 edge, slender enough though it was on 

 this subject, which existed up to his 

 time, but gives a full description of 

 Camerarius" now extensive experimental 

 work. 



It is almost incredible, but it is a fact. 

 that this constitutes the first piece of 

 acual scientific investigation into the 

 quesion of the existence of sex in plants 



that had ever been made, since the date 

 palm had thrown out its first plain and 

 single suggestion more than seven thou- 

 sand years before. 



The Greek and Roman writers on 

 natural history, Aristotle (1), Pliny 

 (8), and Theophrastus (11), had com- 

 mented on the supposed nature of sex 

 in plants ; Theophrastus, and especially 

 Pliny, even citing plainly and definitely 

 the case of the date palm; but it is evi- 

 dent, from the vague and contradictory 

 natvu'e of their views, that they carried 

 on no experiments to determine the 

 facts. This was exactly, however, what 

 Camerarius did. 



He was the first botanist to discover 

 by actual experiment that the pollen is 

 indispensable to the fertilization of the 

 seeds, and that the pollen-producing 

 flowers or plants are therefore male, 

 and the seed-bearing ones female, in 

 nature. Camerarius conducted his ex- 

 periments with spinach, hemp, and 

 hops, in which the pollen and seed-bear- 

 ing plants are distinct, and with Indian 

 corn, or maize. He was likewise the 

 first botanist to discover, two hundred 

 years after maize had been introduced 

 into Europe from America, what seems 

 to us a simple and every-day fact, that 

 on removing the pollen-bearing flowers 

 from the tassel of an isolated corn plant 

 the seeds on the ears remained unfer- 

 tilized. 



PREPARING WAY FOR BREEDERS 



The outcome of his experiments, to- 

 gether wath the results obtained with 

 the other plants mentioned, enabled 

 Camerarius (2) to come to this conclu- 

 sion regarding sex in plants (p. 28) : 



"They behave indeed to each other 

 as male and female, and are otherwise 

 not difi^erent from one another. They 

 are thus distinguished with respect to 

 sex, and this is not to be understood, 

 as is ordinarily done, as a sort of com- 

 parison, analogy, or figure of speech, 

 but is to be taken actually and literally 

 as such." 



We have thus reached another defi- 

 nite landmark in plant breeding. First, 

 the date palm suggested the idea that 



^Letter concerning the sex of plants. 



