398 PROF. J. PERCIVAL ON THE OCCURRENCE OF 
was increased. In some of these cases I removed the blade or 
the primary leaf with forceps as soon as it was possible to do so. 
The petiole of this leaf rather unexpectedly continued to grow 
until it reached a length of an inch or an inch anda half. In 
it crystals appeared just the same as when the blade was left 
attached, from which it may be concluded that the material 
Fig. 1. 
Seedling of Trifolium hybridum. a, lines of crystals. 
supplying the caleium and the oxalic acid is derived from the 
reserve-food of the cotyledon, the blade of the leaf supplying 
nothing from which the erystals of oxalate in the petiole are 
produced. In most cases where the blade of the primary leaf 
was removed there was an increase in the number of crystals in 
the petioles of the cotyledons, and they were developed slightly 
