Roots of Some Rosaceous Genera. 61 
condition in various cork cells which show special reactions to 
certain reagents. This fact has been suggested as a possibility 
by De Bary, but since in the case in point the species of 
Prunee and Pomee were uniform in their results with those 
from the oak stem, I am inclined to consider that they are not 
so useful as tests for cork when the amount of cork present is 
quite small. 
(c) Presence of Nuclei in Cells of the Cork Region—The 
stains which were employed for the purpose of demonstrating 
the nuclei were Bismarck brown, hematoxylin and picroni- 
grosin. By the aid of these stains nuclei were found in 
Potentilla norvegica, both in the flattened uniseriate layer of 
cells and in the multiseriate layers, even so far as where the 
layers were sloughing off. In Geum album and G. atrosangui- 
neum nuclei are observed in the outermost layer of large cells; 
when the periderm consists of five layers of cells, nuclei are 
also found in the layers of small cells in the first species. In 
Fragaria indica nuclei are present in the second multiseriate 
layer of cells. In Waldsteinia geoides nuclei have been noted 
in the eighth layer of cells of the periderm, the nuclei being 
found both in the cells with and without pigmented contents. 
In Agrimonia Eupatoria nuclei are found both in the uniseriate 
layer containing brown pigment, and in the multiseriate zones, 
and can be recognized even so far out as the eleventh row of 
cells. Nuclei are shown in the phototype of Agrimontia, but 
this root is a comparatively young one. In Agrimonia parvt- 
fiora nuclei are demonstrated in the third uniseriate layer, as 
well as in the third multiseriate one. In Alchemilla pyrenaica 
nuclei are found in the eighth row of the periderm, and in 
Spirea Filipendula in the tenth periderm layer. In Auédus 
occidentalis nuclei are noted both in the uniseriate and multi- 
seriate layers, being present even in the eighth row of the 
periderm. In Rosa nuclei are detected in the eighth row of 
the periderm ; these may persist both in the cells containing 
pigment and in those devoid of pigment. In Prunus virginiana, 
