130 MISSOURI BOTANICAL GARDEN BULLETIN 
and to meet these requirements ample provision was made in 
the fill. 
When the construction work was completed the condition 
of the front range was such that a fill of four feet and in some 
places in the fern house of as much as ten feet was necessary. 
While the deeper places in the fern house were, so far as 
possible, utilized in the establishment of the valley and pools, 
it is safe to say that an average fill of fully four feet was 
necessary throughout the front range. he entire fill, 
amounting to about 3,000 yards, was constructed out of rich 
top soil. Before work was begun on the new range, the sur- 
face soil covering the area to be occupied by the new conser- 
vatory was stripped off and piled to one side. Out of this 
reserve about one-third of the fill was constructed. The 
remainder was obtained from a large compost heap which 
has been accumulating in the Garden for a number of years 
and which furnished an ideal medium for plant growth made 
up, as it was, of rich soil and decomposed vegetable matter. 
- To insure a constant future supply of certain essential plant 
foods, raw crushed bone was mixed with the soil as the latter 
was brought into the houses. Soil cars and a narrow gau 
tramway laid directly to the soil piles greatly facilitated the 
filling of the houses. 
As soon as the fill reached the top of the piers supporting 
the steam coils, a four-inch concrete retaining wall was built 
against the pipes and extending slightly above them. Against . 
this wall the soil was banked, resulting in almost the com- 
plete concealment of both the coils and the wall and prevent- 
ing at the same time the excessive drying of the soil in the 
immediate vicinity. 
In conservatories in which the plants are displayed on? 
benches and in which the planting is of the usual formal type, 
the walks are generally fixed in their position with almost 
the same permanence as the building itself. In the front 
range of the new conservatory, however, the planting plan 
adopted marks a decided departure, the desired effect being 
that of an informal landscape throughout. The walks, there- 
fore, have been located in such a manner as to present to 
the visitor the greatest number of pleasing and picturesque 
bits of landscape and at the same time to render all of the 
plants individually as accessible as possible. The paths are 
made with a cinder foundation and a light surface dressing 
of sand. With this type of construction, the position of the 
walks can be readily shifted without much labor or expense, 
should this at any time seem desirable. 
The following accounts will give some idea of the contents 
and arrangement of each individual house: 
