But Camerarius' chief composition on the subject of sexuality
in plants is his letter 'De sexu Plantarum,' which is often mentioned 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 18th
century, and contains more profound observations than were
made by any other botanist before Koelreuter. The style contrasts 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 experiments on sexuality intelligible. The whole tone of the letter
shows that Camerarius was deeply impressed with the extraordinary 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.'
