iv PURSUIT OF KNOWLEDGE 81 



the parts of the flower of maize which receive pollen 

 were cut away, the cobs which afterwards appeared were 

 found to be devoid of seed. 



By these and other experiments Camerarius converted 

 into scientific truth the conjectures as to sexes of plants 

 held by gardeners and botanists almost from the days of 

 the Garden of Eden. Science had to wait, however, 

 nearly one hundred and fifty years longer before the 

 mechanism of fertilisation was completely analysed. 

 It was Dr. Robert Brown who showed in the first half 

 of the nineteenth century that when pollen grains reach 

 the stigma of a plant they send out tubes which pene- 

 trate openings in the outer skin of rudimentary seeds 

 and set up the changes that result in the formation of 

 seeds or embryos. 



It is to the credit of science that many notable 

 advances have been made by men who have not been 

 professionally occupied with scientific work, but have 

 devoted their leisure hours to the study of Nature. Sir 

 Joseph Prestwich was a man of this type. His knight- 

 hood at the age of eighty-three, a few months before his 

 death, was a tardy recognition of scientific services of 

 the highest value to the nation. For forty years Prest- 

 wich was a busy merchant in Mark Lane, London, yet 

 during the years of his City career his contributions to 

 geological knowledge were so many and important that 

 almost every hour of his time out of business must have 

 been occupied with them. 



As a youth, Prestwich's inclinations were all for 

 science, but when it became his duty to enter upon a 

 City career he applied himself to business with all the 

 conscientiousness and earnestness of his nature. 



"Perhaps," says his biographer, "there are few endowed 

 as he was who would have had the moral courage to resist the 

 G.D. F 



