1904] PEIRCE: THE MONTEREY PINE 451 
leaves make, this food will certainly consist mainly of organic 
compounds drawn through, if not exclusively from, the branch 
on which the leaves stand. It is therefore the phloem elements 
upon which the demand for food will be made directly. If 
bundles coming into fallen leaves be cross-sectioned, for example 
at such a point that the bundles lie in the cortex of the branch 
about midway between the epidermis and inner bark, and these 
cross-sections be compared with corresponding ones of the 
bundles of healthy leaves, the differences between the bundles 
will be clear. The simplest way to compare is to cut out and 
weigh the pieces of bristol-board on which camera drawings of 
the sections have been made. Thus the cross-section of the 
normal ‘‘leaf-trace” (phloem, xylem, and enclosed pith) weighs 
0.429, that of the “‘leaf-trace” of a group of the galled leaves 
weighs 0.2108"; the xylem of the former 0.0828", the phloem 
0.335%"; the xylem of the latter 0.0528", the phloem 0.1552". 
That is, the normal ‘“leaf-trace’’ is more than twice as large as 
that of the galled cluster, the xylem of the normal one anda 
half times the galled, while the phloem of the normal is also 
more than twice that of the galled. If one judge the efficiency 
of tissues by the extent to which they are developed—a criterion 
by no means above criticism—the conclusion is forced upon one 
that, so far as one year old leaves show, healthy leaves have 
more work done in them than do galled leaves. This work is of 
various kinds. First, more water and mineral solutes pass 
through the bundles into normal than into galled leaves, and 
more water is transpired from healthy than from diseased leaves. 
Second, more food is made in normal than in galled leaves, 
assuming that the greater amount and more favorable exposure 
of chlorophyll-containing tissues in normal leaves is a safe index. 
Third, more food is removed through the phloem to other parts 
of the plant from healthy than from galled leaves. Although 
the galled leaves nourish larval insects, the development of their 
conducting tissues is less than that of normal leaves. The pro- 
cesses especially characteristic of leaves—food-manufacture and 
the attendant movements of solutions up and down the leaf—are 
less active in galled than in healthy leaves, and the conducting 
