CALCIUM OXALATE IN SEEDLINGS OF ALSIKE. 397 
With increasing age a very few crystals may sometimes be 
noticed along the central vascular bundle running through the 
cotyledons, especially when the latter are of large size, and 
occasionally one or two may develop just within the hypocotyl ; 
but usually a sharp line of demarcation exists in the petioles, 
beyond which no crystals form. As soon as the blade of the 
primary leaf can be detected, crystals begin to appear in it along 
the vascular bundles. The crystals are most abundant near the 
edges of the folded leaf, and develop backwards along the bundles 
towards the midrib. They are produced most abundantly and 
rapidly along the second and third pair of vascular bundles 
nearest the apex of the leaf, a slightly smaller proportion occur- 
ring along the short upper portion of the midrib-bundle (fig. 1, 
p- 398). With increasing growth in length of the petiole of the 
primary leaf, the simple blade is pushed forward and unfolds ; 
stipules are developed also. Crystals soon form in the petiole in 
small numbers, and it was noticed that they are more abundant 
in the upper than in the lower portion of the same petiole; a 
similar development and distribution is seen in the leaves which 
arise subsequently. Along the straight unbranched bundles of 
the stipule crystals are produced in especial abundance, almost 
as scon as in the primary leaf-blade veins, and earlier than those 
occurring in the petiole. 
I was able to keep the plants growing in distilled water without 
calcium other than that originally contained in the seed for five 
or six weeks, during which time the simple primary leaf and one 
or two fully-developed trifoliolate ones were produced. The third 
leaf was usually very minute and contained very few crystals. 
The fact that crystals are formed in the first foliage-leaf 
before it is unfolded, and when it is only just visible to the naked 
eye, suggested that their production is not entirely dependent 
upon carbon assimilation. In order to prove this point, plants 
were grown in distilled water in an atmosphere free from carbon 
dioxide. The plants grew for 20 days and unfolded their 
primary leaves. An examination of them at different times 
during this period showed the presence of crystals distributed 
in a manner simiar to that in plants grown in the ordinary 
way. 
Experiments were carried out with seedlings grown in Knop’s 
solution and in ordinary garden-soil. The distribution of the 
crystals was the same as that indicated above, but their number 
