2 INTRODUCTION TO EMBRYOLOGY OF ANGIOSPERMS 



It was only with the invention of the microscope that actual 

 observation of the sexual cells took the place of conjectures. 

 Leeuwenhoek (1677) 1 discovered the sperms of some animals but 

 mistook them at first for "Wild animalcules" arising in the seminal 

 fluid by some sort of putrefaction. 



In his "Anatomy of Plants," Grew (1682) made the first explicit 

 mention of the stamens as the male organs of the flower. 

 He thought that the pollen grains, by merely falling upon the stigma, 

 transmitted to the ovary a "vivifick effluvium" which prepared it 

 for the production of the fruit. 



Rudolph Jakob Camerarius (1694), Director of the Botanical 

 Garden at Tubingen, approached the matter more scientifically. He 

 observed that in a female mulberry tree, which was growing without 

 any male plants in the vicinity, the fruits contained only abortive 

 seeds. Inspired by this discovery he next took some female plants 

 of Mercurialis annua and kept them in pots completely isolated from 

 the influence of male plants. Here too, he found that, although the 

 plants grew well, not one of the fruits contained a fertile seed. This 

 encouraged him to make further observations, which he summarized 

 in a famous treatise called "De sexu plantarum." He carefully de- 

 scribed the flower, anthers, pollen, and ovules. On removing the 

 male flowers (globuli) of Ricinus before the anthers had shed and 

 preventing the growth of the younger ones, he never obtained any 

 perfect seed but only empty fruits which withered and fell to the 

 ground. A similar lack of seed formation was noted in Zea mays 

 when the stigmas had been removed from the young ear. In con- 

 clusion he said: "In the plant kingdom, the production of seed, 

 which is the most perfect gift of nature and the general means of 

 maintenance of the species, does not take place unless the anthers 

 have previously prepared the young plant contained in the ovary." 

 To the anthers, in his opinion, was to be attributed, therefore, the 

 role of the male sexual organs just as the ovary with its style was 

 considered the female sexual organ. 



We thus see that although Camerarius was not clear about the 

 exact manner in which the pollen functioned, he nevertheless made 

 a notable contribution to our knowledge by showing that some kind 



1 Dates in parentheses refer to works listed in the bibliography at the end of 

 each chapter. 



