LESSON XXXII 



THE CHIEF DIVISIONS OF THE VEGETABLE KINGDOM : 

 EQUISETUM : SALVINIA : SELAGINELLA 



In the XXVIth Lesson (p. 304) it was pointed out that a 

 thorough comprehension of the structure and development 

 of Polygordius would enable the student to understand the 

 main features of the organisation of all the higher animals. 



In the same way the study of the fern paves the way to 

 that of the higher groups of plants, all of which, indeed, differ 

 far less from the fern than do the various animal forms con- 

 sidered in Lessons XXVI — XXIX from Polygordius. We 

 saw that the differences between these includfed matters of 

 such importance as the presence or absence of segmentation 

 and of lateral appendages, the characters of the skeleton, 

 and the structure and position of the nervous system. In 

 the higher plants, on the other hand, the essential organs — 

 root, stem, and leaves — are, save in details of form, size, &c., 

 practically the same in all : the tissues always consist of 

 epidermis, ground-parenchyma, and vascular bundles, the 

 latter being divisible into phloem and xylem : the growing 

 point both of stem and of root is formed of meristem, from 

 which the permanent tissues arise ; and the gro\nng point of 



