THE ENDOSPERM OF ANGIOSPERMS 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 150 
JoHn M. COULTER : 
In a recent analysis of all the available testimony in reference 
to the morphological nature of the endosperm of angiosperms, it 
seemed clear that certain conclusions might be reached, and the 
purpose of the present paper is to state them. 
It has been assumed that the endosperm must be either gameto- 
phytic tissue or sporophytic tissue, and the arguments for each 
view are familiar. The perplexity has arisen chiefly from the 
feeling that gametophyte and sporophyte must be subject to rigid 
definition. When definitions become rigid, ideas become rigid 
also, and nature is always playing havoc with rigidity. If gameto- 
phytes and sporophytes are defined as x and 2x structures, respec- 
tively, straightway x sporophytes and 2x gametophytes are dis- 
covered. If sporophytes are defined as structures produced by 
fertilized eggs, the definition is contradicted by numerous sporo- 
phytes that are not the product of fertilization. In this way, every 
criterion suggested has found its contradiction. It is becoming 
evident that definitions must be elastic and not rigid, and that 
general situations rather than definite categories must determine 
conclusions. We have moved so far beyond the rigid categories 
of the days of metamorphosis, that it is surprising to find an equal 
rigidity in the days of alternation of generations. 
Without citing an extensive and familiar literature, attention 
may be called to the various claims that have been made as to the 
morphological nature of the endosperm of angiosperms. 
Ever since the comparative morphology of the vascular groups 
was uncovered by HormetsreEr, belief has been general that the 
endosperm of angiosperms is gametophytic tissue which develops 
after fertilization. It was easy, even in the days of HoFMEISTER, 
and much more so now, to obtain from gymnosperms what seems 
to be abundant confirmation of this claim. Throughout that group 
there is a distinct tendency to differentiate eggs earlier and earlier 
Botanical Gazette, vol. 51] ‘ [380 
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