DIFFICULTIES IN ANALYSIS. 129 
275. But the minuteness of the organs or parts to be 
studied is often discouraging even to the accurate student, 
much more to the careless one. To overcome this, skill in 
dissection and a dauntless courage in observation are indis- 
pensable. Moreover, there is often much ambiguity in the 
nature of the subject. For example, whether the Geraniums 
are herbs or shrubs; whether the flowers of Petunia are reg- 
ular or irregular; whether the Pear leaf is ovate or oval, 
&e. Experience will at length diminish this difficulty. 
276. The exact limits between the classes, the cohorts, &c., 
are not always easily defined. For example, is Trillium an 
Exogen or an Endogen? Its netted leaves indicate the for- 
mer, but its flowers being three-paried throughout, and iis 
seeds with one cotyledon, prove it to be an Endogen. Again, 
is Spring Beauty an Exogen or an Endogen? Its leaves 
seem, at first, parallel-veined, but as its flowers are five-parted 
it is an Exogen. 
277. Angiosperms will be readily distinguished from Gym- 
nosperms, if we remember that almost all the latter are ever- 
green trees, like the Pines, Cedars, Larches, &e. 
278. The industrious student will very soon find himself 
so well acquainted with the different characters of the cohorts 
that he will in analysis refer his plant at once to its right 
cohort, without consulting the previous parts of the table. 
This is desirable; and a thorough acquaintance with the 
275. What of the minuteness of the organs of some plants? What of the 
ambiguity of the plants themselves? What will soon diminish this diffi- 
culty? Mention examples of this ambiguity. 
276. Are the limits of the classes, cohorts, genera, &c., always clear? 
How do we know that the Trillium is an Endogen? that Spring Beauty is 
an Exogen? 
277. How may the Gymnosperms be quickly distinguished ? 
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