130 Laboratory Notes . 
FUCH SIN-IODINE-GREEN AS A CROSS-STAIN 
FOR TISSUES. 
I have lately found the above, hitherto, I believe, only used as 
a double nuclear stain, useful in differentiating tissues. 
The sections in dilute glycerine are covered while on the slide 
with a mixed solution of Fuchsin and of Iodine-green in 50% alcohol. 
Usually two or three minutes are enough to stain them a deep purple. 
They are then washed in absolute alcohol and transferred almost 
immediately to clove-oil and Canada balsam, the whole process 
occupying less than five minutes. 
The amount of the differentiation varies as the length of the 
washing, but I have found it best not to carry this too far. 
The lignified and suberized elements are stained a deep red 
purple, while the parenchyma and unlignified tissues generally have 
their walls blue. 
Sometimes in these latter there is a great variety in the shade 
of blue, and this corresponds to a morphological difference in tissue; 
so that in a stele the pericycle, phloem, parenchyma and pith may 
all have their walls a different shade. 
The great advantage of this method is its quickness and the 
ease with which a hand-cut series may be permanently mounted, as 
well as the sensitiveness of the different tissues to the stain. 
The results are not equally good in all cases, but I have found 
the method answer admirably with vascular cryptogams and 
dicotyledonous seedlings. , 
I am not able to answer for its permanency, though sections 
stained in this way nine months ago shew little change; but 
however this may be the method is certainly useful in differentiating 
vascular tissues very quickly for immediate observation. 
E. C. 
University College, 
June, 1902 . 
