Science |3ri>gress. 



No. 6. August, 1894. Vol. I. 



RECENT WORK ON THE MORPHOLOGY OF 

 TISSUES IN THE HIGHER PLANTS. 



I^HE classification of tissues proposed by Sachs in his 

 Text-book of Botany has been until quite recently 

 the arrangement most familiar to English students. Sachs' 

 three systems of tissue, the Dermal, the Fascicular, and the 

 Fundamental or Ground Tissue, have, however, a merely 

 descriptive value, and cannot claim to rest on any consistent 

 basis, whether physiological or morphological. The first 

 two systems are indeed broadly characterised by function, 

 but the third is obviously made up of the most hetero- 

 geneous constituents, performing every kind of physiologi- 

 cal work. 



That the arrangement was never intended to be a strictly 

 morphological one is sufficiently shown by the fact that the 

 Dermal Tissue includes not only the epidermis, but the peri- 

 derm, a secondary formation which may arise from any 

 tissue whatsoever, and is only in exceptional cases of 

 common origin with the epidermis. 



De Bary's great work on the Comparative Anatomy of 

 the Phanerogams and Ferns, invaluable for the immense mass 

 of well-ordered detail which it contains, and for its critical 

 treatment of certain developmental questions, did little for 

 the general morphology of tissues. The " Forms of 

 Tissue," to which the first part of the book is devoted, are 

 classified by purely histological characters, i.e., according to 

 the mature structure of their elements. The second part 



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