CHAP, i.] Rudolph Jacob Camcmrins. 387 



But Camerarius' chief composition on the subject of sexuality 

 in plants is his letter ' De sexu Plantarum,' which is often men- 

 tioned but apparently little read, and which he addressed to 

 Valentin, Professor in Giessen, on Aug. 25, 1694. It is the 

 most elaborate treatise on the subject which had as yet been 

 written, or indeed which appeared before the middle of the i8th 

 century, and contains more profound observations than were 

 made by any other botanist before Koelreuter. The style con- 

 trasts favourably with the style of the writers of the time, and is 

 thoroughly that of modern natural science ; it combines perfect 

 knowledge with careful criticism of the literature of the subject ; 

 the construction of the flower is explained more clearly than it 

 had ever been before, or was again for a long time after, and 

 expressly for the purpose of making the meaning of his experi- 

 ments on sexuality intelligible. The whole tone of the letter 

 shows that Camerarius was deeply impressed with the extra- 

 ordinary importance of the question, and that he was concerned 

 to establish the existence of sexuality by every possible means. 



After detailed examination of the parts of the flower, the 

 anthers and pollen, the behaviour of the ovules before and 

 after fertilisation, the phenomena of double flowers and similar 

 matters, from all which he cautiously deduces the meaning 

 of the anthers (apices), he proceeds to bring forward direct 

 proofs. He says, ' In the second division of plants, in which 

 the male flowers are separated from the female on the same 

 plant, I have learnt by two examples the bad effect produced 

 by removing the anthers. When I removed the male flowers 

 (globules) of Ricinus before the anthers had expanded, and 

 prevented the growth of the younger ones but preserved the 

 ovaries that were already formed, I never obtained perfect seeds, 

 but observed empty vessels, which fell finally to the ground 

 exhausted and dried up. In like manner I carefully cut off 

 the stigmas of Mais that were already dependent, in consequence 

 of which the two ears remained entirely without seeds, though 

 the number of abortive husks (vesicularum) was very great.' 



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