160 Magnus. — On Aecidium graveolens (Skuttlew.). 
most part retracted only from the longitudinal walls, while 
remaining more or less in contact with the short horizontal 
or oblique walls (Fig. 10). These contracted cell-contents then 
resemble a tube placed longitudinally in the empty cells, and 
if the plasmolyzed contents are not retracted from the common 
transverse wall of neighbouring cells, they present the appear- 
ance of a continuous tube passing through the cell-cavities. 
Eriksson’s figure appears to me to strongly suggest such 
plasmolytically contracted cell-contents, although it must be 
borne in mind that I have not examined Eriksson’s pre- 
parations. 
It is well known that the wood of the young Barberry is 
yellow, and that this is caused by the yellow cell-sap which 
is found even in the young wood-cells, thus indicating that 
the colouring-matter exists in a state of solution, and not 
in the form of yellow granules. The yellow colouring-matter 
of the granules observed by Eriksson in the tubes, which 
appear to me to be nothing more than plasmolyzed cell- 
contents, may be connected in some fashion with the colouring- 
matter of the young wood-cells. In making preparations, if 
the cells are cut across, the yellow sap flows out into the 
water, and then they appear colourless. The granules of 
the young wood-cells do not appear yellow. I cannot decide 
whether the yellow tint of the granules figured by Eriksson 
may not be due to the colouring-matter of the wood-cells seen 
through the cambium-cells (especially as Eriksson mentions 
in a foot-note to his paper in the Ber. d. Deutsch. Bot. Ges., 
Vol. xv, 1897, p. 229, that all the granules appeared yellow, 
and not as the lithographer has by mistake indicated, a few 
of them only), or whether they represent the first appearance 
of the yellow colouring-matter of the wood-cells. In no case 
have I been able to observe in the mycelium of any of the 
Uredineae not exposed to the light any trace of yellow 
colouring-matter. Even in the mycelium of the cortical 
parenchyma and the phloem no colouring- matter is found. 
It seems to me that these results are of special interest, 
because Eriksson has lately maintained the theory of the 
