210 THE FLORAL WORLD AND GARDEN GUIDE. 
first lot should be put in about the middle of November; and to 
maintain a regular supply, introduce successional batches at intervals 
of a fortnight or three weeks. The roots should be placed in 
an upright position, with very little soil between them. They may 
also be put into deep boxes, and be covered closely to exclude the 
light, and the boxes be placed under the stage of the greenhouse, or 
ina cucumber house. The leaves must be developed in perfect 
darkness, or they will be inferior in quality. 
THE POTTERY TREE OF PARA. 
BY JOHN R. JACKSON, 
Royal Gardens, Kew. 
=e \MONGST vegetable economic products the barks of 
| various plants hold a prominent place, whether for 
medicinal, manufacturing, or other purposes. The 
structure and formation of all barks are more or less 
z similar, though the contents of the cells vary much in 
different plants,—thus we have soft or fibrous, hard or woody, and 
even stony barks, and the bark of the pottery tree of Para is a 
notable example of this latter. To outward appearance, the forma- 
tion of the bark in many plants would appear to bear no relation 
one with another, as, for instance, the cork of commerce compared 
with its near ally the bark of the common oak, and again with the 
fibrous barks of many of our British trees. Naturally, the bark of 
a tree is, at first, composed of uniform cellular tissue, similar to the 
tissue of the central portion of the stem. The formation of the 
layers in the fully-developed bark is on the reverse system to that 
of the woody layers of the stem, the inner portion being the most 
vascular, and the outer portion the most cellular. Between the 
wood and the first formation of bark lies the cambium layer, a single 
series of nucleated cells, which originally are connected with both 
wood and bark, and perform certain functions in the formation of 
the woody fibres of the inner bark, and likewise in adding to the 
cells of the medullary rays of the wood. The innermost part of 
the bark next the wood, or rather next the cambium layer, is called 
the liber, or endophleum; next to the liber, which is the fibrous 
part, the cellular part is placed, called the mesophleum, or middle 
bark ; and next that the epiphleum, or outer bark. These three 
divisions are usually included under the general term of cortical 
layers. It is from the liber, or inner bark, which is composed of 
fibres more or less long and tenacious, that our most valuable com- 
mercial fibres are obtained. 
In some plants the fibrous system prevails through the inner 
bark ; but we shall have occasion to speak more fully upon these 
particular kinds at another time. What we have to deal with at 
present is a noted example of the harder, more woody, or more 
silicious barks, which example is to be found in the Para pottery 
tree. This is a large tree of very straight and slender growth, 
