156 THE HISTORY OF BIOLOGY 



version of metals effected by the alchemists, and presumes that, just as a 

 vegetable species can, by repeated unilateral crossing, be transformed into 

 another, one day man will learn to convert, by a necessarily gradual process, 

 one metal into another; in further evidence of which he finds a correspond- 

 ence between the pollen and the sulphur of the alchemists, proved by the 

 fact that pollen can be used as a means of reducing metal oxides, though this 

 is easily explained when the pollen is burned to coal, which has a reducing 

 effect. Moreover, the female sexual product is, in his opinion, "mercurial." 

 It is thus in the sphere of practical experiment that Koelreuter's greatness 

 lies; in this he is a pioneer, and his experiments in crossing were justly taken 

 as a model until Mendel's far more deeply thought-out experiments became 

 known. Koelreuter shared the fate of the latter, the greatest of his succes- 

 sors, in his works' being for a long time entirely neglected; it was not until 

 long after his death that they were rescued from oblivion and accorded the 

 appreciation they deserved. 



The same fate of being neglected by contemporary and immediately suc- 

 ceeding ages was suffered by Christian Conrad Sprengel, whose investi- 

 gations into the fertilization of flowers were carried out in association with 

 Koelreuter's. Born in 1750 at Brandenburg, the son of a clergyman, Sprengel 

 studied theology and languages, afterwards devoting himself to the tutor's 

 profession. He was for some years a schoolmaster in Berlin and later became 

 rector at Spandau. After several quarrels with his superiors, his pupils, and 

 their parents he was dismissed with a pension in 1794 and then lived in 

 Berlin in a solitude that increased year by year until he died in 1816. His 

 irascible temperament contributed both to his failure as a teacher and to 

 his subsequent isolation; it was aggravated by the utter lack of understanding 

 with which his contemporaries received the results of the botanical re- 

 searches that had represented the chief interest of his life. He was unable 

 to print his last botanical writings, with the result that during his last few 

 years he applied himself to philology, apparently with but little success. 



Sprengel' s experiments on plant-jertilixation 

 The work which at last brought his name to the knowledge of posterity 

 is his Das entdeckte Geheimnis der Natur im Ban und in der Bejruchtting der Blumen, 

 published in 1793. Under this somewhat pretentious title he collected a large 

 number of observations in connexion with the florescence of plants, and on 

 them bases a general theory of fertilization in the vegetable kingdom, which 

 in its essentials still holds good today. In conformity with his theological 

 upbringing he was fully convinced of nature's having been preconceived by 

 the wisdom of the Creator down to the minutest detail, and he consequently 

 set about trying to discover for what useful purpose the different parts and 

 properties of the flower were intended. As a result of his inquiries into this 

 subject he found, to begin with, that the flowers' nectaries are always pro- 



