150 Mr. Brown on some remarkable Deviations 
become visible unless the seed be placed in a situation favourable 
to germination, that very different directions may be given to its 
radicular extremity, according to circumstances which we have it 
in our power to regulate. 
There is a fourth kind of anomaly in the structure of certain - 
seeds, which, as I have formerly described it*, I shall here notice 
in few words. It is that which takes place in certain Aroidee, 
especially in some species of Calladium. In these, the nucleus of 
the seed is not properly a monocotyledonous embryo, but has an 
appearance and economy more nearly resembling those of the 
tuber of a root ; for, instead of being distinguishable into a coty- 
ledon, a plumula and radicula, and of germinating in a determi- 
nate manner and from a single point, it is composed of a mass 
whose internal structure is uniform, and on the surface of which 
frequently more than one germinating point is observable. 
None of these anomalies appear to me materially to lessen the 
importance of the characters derived from the seeds of plants; 
but they evidently render a minute attention to every circum- 
stance absolutely necessary in all attempts either to deduce affini- 
ties or establish genera from this source; and they especially de- 
monstrate the necessity of carefully ascertaining the state of the 
unimpregnated ovarium; for, while its structure remains unknown, 
that of the ripe fruit can never be thoroughly understood. 
* Prodr, Flor. Nov. Holl. p. 335, 
EXPLA- 
