60 
MANAGEMENT OF PLANTS IN FORCING. 
with no power of extending horizontally beyond a specifically limited diameter, 
a stem is formed." 
Few persons may have opportunity to watch the gradual progress of a stem 
advancing far in height ; yet in a fine collections of palms — as, for instance, that 
of Messrs. Loddiges, Hackney, — specimens may be seen, which exhibit, perfectly, 
the external habits of exogenous stems. Thus in the cocoa-nut palm the external 
coat is rough ; it is formed of the bases of decayed leaves, which, falling ofi^, afford 
traces of their position, and this having been, as before stated, more or less circular, 
the trunk is marked by a series of scars corresponding therewith. 
2. The leaves of endogens are also peculiar. They are usually straight-veined ; 
take, for example, the leaves of any of the hardy farinaceous plants, wheat, barley, 
&c., and of the reeds ; or, in the liot-house, those of Canna (Indian shot), or its 
congeners in the Order Marantacese. Compare this general and more simple 
structure (though it be not quite absolute) with that of the multiform varyings and 
ramifications in the foliage of exogens^ and a marked difi^irence will be discerned ; 
of causes we know nothing, but these are facts which cannot be impugned. Finally, 
3. The seeds are equally simple, they have either but one seed-lobe, (Cotyledon)^ 
or if the rudiment of a second be present, it is imperfect, and not exactly opposite 
to the true lobe. Of this, more must be said when we come to the investigation 
of seeds. 
The third great class — Acrogens — comprises those orders of plants which, till 
lately, were termed Cryptogamous. According to Lindley, their substance is com- 
posed of cellular tissue chiefly, the cells spheroidal or elongated. The stem either 
advances perpendicularly from its point, or irregularly in all directions from one 
common point. Seeds, properly speaking, there are none ; consequently, the 
plants rank under the Order Acotyledones, or without seed-lobes. This class 
comprises the ferns, mosses, lichens, algae, sea-weeds, and funguses. 
The fourth class — Dictyogens — we consider as an anomaly not worthy of much 
interest ; and, in fact, when we find only the example Smilax in proof that the stem 
has the structure of an endogen, the root that of the stems of exogens nearly, and 
trace it among the Exogens order 256 of the Natural System, we perceive no reason 
to separate Smilacece-^i\\Q Sarsaparillas-— from the other orders of complete plants. 
Our systems of Botany, in their attempts to simplify, afford proof, already 
but too evident, that a natural arrangement involves perplexities which the 
thousands of new introductions must inevitably tend to increase. 
MANAGEMENT OF PLANTS IN FORCING. 
As the production of superior fruit in a forced state, and at an early season 
of the year, is considered the best evidence of a good fruit-grower ; so the produc- 
