78 
METHODS IN PLANT HISTOLOGY 
the culture in a drop of water or culture solution on the cover, and 
invert the cover over the hole. A little.water added at the edge 
of the pasteboard from time to time will'keep it from warping and 
will at the same time provide a constant moist chamber. 
Fig. 18.—Another hanging-drop culture 
In collecting material for mitotic figures in anthers it is necessary 
to examine fresh anthers, if one wishes to avoid a tedious and uncer¬ 
tain search after the anthers have been imbedded. By teasing 
out a few cells from the apex and a few from the base of the anther 
the stage of development is readily determined, and anthers which 
do not show the desired stages can be rejected. By allowing a drop 
of eosin or methyl green to run under the cover the figures are more 
easily detected. The actual progress of mitosis has been observed 
in living stamen hairs of Tradescantia. 
MICROCHEMICAL TESTS 
Botanical microchemistry has developed to such an extent that 
it has become an independent subject, like bacteriology. We shall 
consider only the commonest tests which are needed constantly by 
students of morphology. For a thorough presentation of the chem¬ 
istry of the cell, we are looking forward with great anticipation to a 
forthcoming book by Dr. Sophia Eckerson, whose critical tests and 
analyses we have observed for many years. In the meantime, 
Pflanzenmikrochemie , by Dr. O. Tunmann (Gebriider Borntraeger, 
Berlin), is recommended to those who read German. Zimmerman’s 
Botanical Microtechnique (Henry Holt & Co., New York) is still 
recommended to those who must rely upon English. We shall give 
only a few tests, but in considering the various stains we shall indicate 
the effect of each stain upon the various plant structures. 
Starch.—Mount the starch or starch-containing structures in 
water, and allow a drop of iodine solution to run under the cover. 
Starch assumes a characteristic blue color. The solution may be 
prepared by dissolving 1 g. of potassium iodide in 100 c.c. of water 
and adding 0.3 g. of sublimed iodine. A strong solution of iodine in 
alcohol (about 1 g. in 50 c.c. of absolute alcohol) keeps well. A drop 
