24 HISTORY OF BOTANY 



insisted that ferns grew from the " dust " produced on the 

 backs of their leaves. Belief in abiogenesis was almost 

 universal, and even as late as the end of the sixteenth 

 century competent botanists thought that Fungi developed 

 spontaneously from damp soil. Caesalpino, for instance, 

 asserted that seedless plants were " bred of putrefaction.'* 

 Ignorance of Cryptogamic Botany indeed was the chief 

 cause of the long delay in discovering a unity of plan 

 throughout the vegetable kingdom, a unity first brought 

 to light by Hofmeister's epoch-making work half-way 

 through the nineteenth century, although data had been 

 accumulating for at least fifty years before his time. 



From the earliest classical period plants were known 

 to be living organisms, but this fact seemed to have been 

 recognised only subconsciously, so to speak, for physio- 

 logical investigations were not undertaken until well on 

 in the eighteenth century. In this respect botany lagged 

 far behind her sister science zoology. William Harvey, 

 for instance, discovered the circulation of the blood in 

 animals in 1628. Up to the sixteenth century all that 

 was known about plant physiology could have almost 

 been written on a sheet of notepaper. Naturally also 

 the first observations were made as comparisons between 

 plants and animals. The plant was a fixture and obtained 

 its food supply from the soil, and that was practically all 

 that was understood as to the physiology of nutrition ; 

 the part played by the leaf in relation to carbon assimila- 

 tion was of course quite unknown. Had plants sex like 

 animals ? Theophrastus seems to have had a suspicion 

 that at least some of them had, but his guarded hints 

 were neglected, and even Caesalpino, though he founded 

 his classificatory system on the fruit and seed, denied 

 that plants had sex. Malpighi, towards the end of the 

 seventeenth century, thought that stamens and floral 

 leaves merely purified the sap that went to nourish the 

 developing seeds. In spite of the fact that plants were 

 fixtures, some of them were seen to exhibit movements 



