240 WILLIAM TRELEASE— TWO NEW TERMS : 



of vascular tissue in the cormophytes) indicates the significance for 

 phylogeny and morphology of the emphasis that is here laid on the 

 coordination of thallophyte, cormophy taster and cormophyte in 

 botanical terminology. 



The second term proposed refers to what is commonly called the 

 endosperm of angiospermous plants, sometimes spoken of as sec- 

 ondary endosperm. Very probably descriptive botanists will con- 

 tinue for a long time to speak of seeds as being albuminous or 

 exalbuminous according as they possess or lack a food-reserve in 

 the seed, which is used by the embryo in the early stages of germina- 

 tion. They have not been deterred greatly by the difficulty that 

 sometimes exsits in determining quickly whether or not this reserve 

 tissue is really absent or merely reduced to so thin a layer as to be 

 overlooked — though they try to indicate this difference; nor, for 

 practical reasons, by the now very old knowledge that the ambiguity 

 of the word albumen might make the employment of endosperm and 

 perisperm in its place preferable in descriptive botany. Morpholo- 

 gists, however, have adopted the latter terminology of necessity, as 

 indicating respectively food-reserve within or exterior to the embryo- 

 sac or megalospore (as, of course, the name substituted for the in- 

 accurate " macrospore " should have been coined), — "exalbumi- 

 nous " seeds being those in which what would have remained as 

 " albumen " has been used up during the maturing of the seed. 



Quite as great mischief has been wrought here as with the terms 

 thallophyte and cormophyte, by indiscriminate adoption of this 

 betterment. Although the endosperm of a gymnosperm may be 

 homologised with the endosperm of an angiosperm on the apparent 

 but inapplicable ground that both are transient tissues formed within 

 the embryo-sac, it is well known to every botanist that the gymno- 

 spermous endosperm — represented in angiosperms by antipodal cells 

 and synergids — is really homologous with the sexual generation of 

 bryophytes and pteridophytes ; while the angiospermous endosperm, 

 or secondary endosperm, originates from the " endosperm nucleus," 

 — after a process which can be called scarcely anything but fertiliza- 

 tion except through an over refinement of definition. 



If no other considerations were involved, the simplest way might 

 be to speak of the gymnospermous endosperm and its homologue in 



