224 Introduction. [BOOKII. 



nection between the cellular and fibrous elements in the struc- 

 ture of plants. Two fundamental forms of tissue were assumed 

 from the first, the succulent cellular tissue composed of cham- 

 bers or tubes, and, in contrast to this, the elongated usually 

 fibrous or tubular elementary organs, the distinction of which 

 into open canals or vessels and fibres with closed ends continued 

 to be doubtful. The characteristic feature of this period is, that 

 the investigation of the more delicate structure is everywhere 

 closely interwoven with reflections on the function of the ele- 

 mentary organs, and that thus anatomy and physiology support 

 each other, but not without mutual injury through the imper- 

 fections of both. But the physiological interest far outweighed 

 the anatomical with the first phytotomists, who used anato- 

 mical research for the purposes of physiology. 



The imperfectness of the microscope during the whole of the 

 eighteenth century produced a certain disinclination to ana- 

 tomical studies, which were after all only regarded as auxiliary 

 to physiology. The latter had made very important progress 

 without the help of anatomy in the hands of Hales, and later 

 on towards the end of the i8th century in those of Ingen- 

 Houss and Senebier, and thus the interest in phytotomy was 

 almost extinguished. Not only was very little addition 

 made to the contributions of Malpighi and Grew during the 

 1 8th century, but they had to some extent ceased to be 

 understood. 



However towards the end of that time the microscope came 

 again into fashion ; in the compound form it had become 

 somewhat more convenient and manageable ; Hedwig showed 

 how it revealed the organisation of the smallest plants, and 

 especially of the Mosses, and he examined also the con- 

 struction of cell-tissue and vascular bundles in the higher 

 plants. But with the beginning of the present century the 

 interest in phytotomy suddenly rose high again ; Mirbel in 

 France, Kurt Sprengel in Germany made the microscopic 

 structure of plants once more the subject of serious investi- 



