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1914] MANEVAL—MAGNOLIACEAE 17 
This theory is founded mainly on the large number of coin- 
cidences among both dicotyledonous and monocotyledonous aquatic 
plants, and on the fact that all terrestrial monocotyledons exhibit 
the same coincidences. HENSLOW, as well as many others, regards 
the monocotyledons as degenerate (when compared with dicotyle- 
dons), although there is not always agreement as to the cause of 
degeneracy. HENSLOw himself believes an aquatic habit has been 
the principal cause, and points to a number of characteristics of 
monocotyledons and dicotyledons that he considers the result of 
adaptation to a moist or aquatic environment. Among these 
peculiarities are large size of leaves, water storage organs, the 
pseudo-monocotyledonous condition of certain dicotyledons, early 
loss of primary root, and ‘‘endogenous” arrangement of cauline 
bundles. HENSLow remarks: “In the title of my first paper in 
1892 (13), I used the word ‘theory,’ but . . . . I feel justified in 
abandoning the term; for I would maintain that the conclusion 
has passed the stage of hypothesis and probability only, to that 
of a demonstrated fact.’ While it is likely that very few of us 
would be willing to subscribe to this conclusion, yet all must 
agree that such considerations are extremely suggestive, and 
indicate a line of work that is promising, especially if taken up 
experimentally. 
To multiply-examples would probably not add to the force of 
the argument. We see that various competent workers attribute 
anomalies among dicotyledons to a geophilous habit, response 
either to xerophytic or to hydrophytic conditions. Such responses 
result in structural peculiarities in stems, formation of various 
types of underground stems, a pseudo-monocotyledonous habit, 
or division of labor among the cotyledons. When we turn to the 
monocotyledons, we find these peculiarities duplicated, but as a 
rule they are intensified. That their production is related to 
environment seems clearer in the case of dicotyledons than of 
monocotyledons, no doubt because many monocotyledons at 
present live where the prevailing conditions do not seem to neces- 
sitate geophily. The persistence of these peculiarities in such 
environments may be interpreted as retention of past characters. 
It seems then that, on account of many similarities between 
