532 Wisconsin Academy of Sciences, Artsand Letters. 
not suddenly into tlie inner layers. The orange layers are of 
fairly uniform width around the grain, being slightly wider 
on the posterior end, while the outermost violet layers are in¬ 
complete, that is, are broad curved bands on the posterior end 
of the grain, but extend but a short distance down the sides of 
the grain towards the hilum, and in only a, few instances were 
seen to pass entirely around it. This makes, it evident that the 
orange layer does not pass; over in toto into the violet. Still 
even in such cases of transition it is difficult to say to what the 
change is due by which the orange pass into the violet staining 
layers. It may be due to a condensation of the carbohydrate 
material, brought about by the abstraction of water, or to a 
more deeply seated chemical change. 
It is possible that this orange staining substance is carbohy¬ 
drate material which has been brought inside the leucoplast 
but which has not yet fully taken on the nature! of starch and 
the capacity to fix the violet stain. This would seem to be 
more natural than the assumption that starch can show such a 
variable reaction to the same stains. 
In the: development of the cell plate in the onion; root-tip, the 
equatorial zone was found by Timberlake (7) to- become filled 
with a sub-stance that stains strongly with the orange of the tri¬ 
ple stain. This substance appeared to be entirely homogeneous 
and with ruthenium red or iron haematoxylin appeared colorless 
while the cell wall was stained. 
Timberlake says, “The similarity of this substance to that 
of the cell wall, together with its presence in the region of the 
spindle in which the cell wall appears later, I have taken to 
signify the presence of a carbohydrate substance destined for 
the formation of the new cell wall.” 
Wei have thus two cases in which a. transition substance in the 
formation of solid carbohydrates appears, taking the orange 
stain. In, both cases it is formative in nature, the one passing 
over into' the cellulose wall, the other forming starch. 
Wei find the very young starch grains either staining entirely 
or showing a. large proportion of orange. We find an outer 
layer of orange in the older grains, and by following the course 
of development of the starch grain, we are led to believe that 
the orange staining substance in young and old grains is identi¬ 
cal. We also find that the action of diastase causes a larger 
proportion of the grain to take the orange stain. It is further 
