CRYPTOGAMS AND PHANEROGAMS. 249 



with the exception of one cell, which continues the development 

 and gives rise to the nutritive-tissue proper, which is formed in 

 the first instance of primordial cells, and later on of a cellular 

 tissue ; this nutritive-tissue formed in the embryo-sac is termed 

 " endosperm"; in a few instances 1 a tissue which is derived from 

 the nucellus functions as nutritive-tissue, and is termed " peri- 

 sperm." In many plants the seeds, when ripe, contain a very- 

 rich nutritive-tissue, in addition to the embryo, for the purpose of 

 its nourishment during germination. These are termed albu- 

 minous (endospermous) seeds, in distinction to the ex-albu- 

 minous, or those in which the nutritive- tissue is stored in the 

 embryo itself, before it is completely developed, and used for its 

 sustenance. 



In addition to the changes which fertilisation produces in the 

 ovule itself, it also gives the impetus to a series of changes in the 

 entire shoot which bears the ovule. The perianth, stamens, and 

 style, generally wither, because the part they play is at an end ; 

 the wall of the ovary grows and becomes the wall of the fruit 

 (pericarp). The entire gyncecium of a flower, transformed as a 

 consequence of fertilisation, is termed a fruit. It consists of two 

 parts, the pericarp and the seeds, and according to the nature of 

 the pericarp, the fruit is termed a capsule, nut, berry, or drupe. 



The chief characteristic of the Phanerogams does not lie in the 

 formation of the flower (although they may quite properly be 

 termed " Flowering-plants "), because Equisetums and Lycopods 

 have reproductive shoots as highly differentiated as those of 

 certain Gymnosperms and other Phanerogams. As regards the 

 SEXUAL GENERATION the characteristics are found : (1) in its 

 great reduction ; (2) in the transmission of the microspore (pollen- 

 grain) to the macrosporangium, and its germination, with the 

 formation of a pollen-tube (antheridium), the protoplasm of which 

 is not differentiated into spermatozoids 2 ; (3) in the fact that the 

 macrospore (embryo-sac) never leaves its sporangium (nucellus) ;. 

 and further in the Angiosperms, (4) in the peculiar development 

 of the nutritive-tissue in two parts ; and (5) in the great reduc- 

 tion of the archegonium. 



As regards the ASEXUAL GENERATION the characteristic feature is- 

 that this generation is formed whilst the sporangium is still 

 attached to the mother-plant, and for a long time is nourished by 

 it ; and that after the sporangium has become detached from the- 



1 .tiperaceos, Nymph aeaceas. 2 Except in Cycads and Ginkgo. 



