28 Schively—Recent Observations on 
usually necessary to compare many plants or perhaps to 
undertake a series of experiments, frequently repeated during 
many years ; even then the data may be neither satisfactory 
nor convincing to the investigator. A strong and plausible 
hypothesis may be advanced, but the difficulty is to obtain 
direct and sure proofs. 
Considering the various types of flower found upon speci- 
mens of Amp/ucarpea growing in the woods, or upon their 
borders, the opinion might be advanced that there are distinct 
species, some of which never produce purple flowers and their 
legumes. But the experimental evidence is conclusive proof, 
that one plant is capable of bearing all varieties of flower and 
fruit. Yet we cannot determine why in its native haunts, 
Amphicarpea may produce all three forms of legume, some- 
times but two, or again but one. 
The formation of the subterranean legumes has become a 
definite part of the plant’s inheritance, and for many reasons 
may well be regarded as an acquired characteristic rather than 
as an example of indefinite variation, since it is not usual for 
plants to bear fruit in this manner. What factors originally 
operated to cause the production of this type of seed, and to 
fix the result as a habit, it is impossible to say ; but the trans- 
mission is now undoubted. Often, indeed, no aerial legumes 
are formed, and the reproduction of the species is dependent 
solely upon these subterranean seeds. 
While then the germ-plasm cells transmit the tendency to 
form legumes, whose morphological and _ histological features 
differ so greatly from those of the original type, yet when it is 
considered with what ease and rapidity either type of legume 
will respond to changed environmental conditions, the centres 
of variation seem to reside in the somatoplasm, and gradually 
affect the reproductive substance. 
Two flowers in the same stage of development may be 
artificially forced to produce legumes quite different in charac- 
ter. Certain extrinsic factors stimulate, for example, the cells 
