CLASSIFICATION OF TISSUES 183 







further details, as also to the numerous papers on the 

 anatomy of Pteridophyta from the pen of Gwynne- 

 Vaughan, by whose recent death British Botany suffered 

 so grave a loss. 



In 1884 Haberlandt returned to Sachs's point of view 

 of the classification of tissues in his Physiologische 

 Pflanzenanatomie, which, after passing through four 

 editions in the original, made its appearance in English 

 dress in 1914. The idea underlying this work is that the 

 whole architecture of the plant is an adaptation in 

 response to physiological needs, and is thus to be regarded 

 from an entirely different standpoint from that assumed 

 by the pure morphologist. Tissues are classified accord- 

 ing to their functions into dermal, mechanical, absorptive, 

 photosynthetic, conductive, and so on. Haberlandt did 

 not aim at upsetting the purely morphological arrange- 

 ment however, for he recognised that tissues of entirely 

 distinct origin may be modified in the same way to fulfil 

 the same function. The treatise is thus more valuable 

 to the physiologist than to the anatomist, and is especially 

 so to workers in ecological botany, a subject which had 

 begun to be widely studied at the end of the nineteenth 

 century, and which, owing to the labours of Warming 

 and A. F. W. Schimper, assumed such prominence in 

 the early years of the twentieth century. 



Just as in the case of the Cryptogams, an immense 

 number of papers were published from 1860 onwards 

 upon special points in tissue structure and arrangement, 

 or on the minute anatomy of individual genera or species, 

 but it would take us far too long even to enumerate these 

 researches let alone to discuss them. 



ADVANCES IN PHYSIOLOGY 



Let us now consider what progress was being made 

 in physiology during this period. As we have already 

 seen, the whole outlook had undergone a profound change 



