66 BOTANICAL GAZETTE [JULY 
per cent. However, most tissues may be taken from 85 per cent alco- 
hol and covered with that remaining in B, and then transferred from 
that to either 95 per cent or absolute alcohol. 
The flow of alcohol is insured against varying vapor pressures by the 
short capillary tubes in the stoppers which close the upper ends of the 
larger tubes, or if suitable capillary tubing cannot be obtained ordinary 
glass tubes nearly sealed at both ends will do quite as well. In either 
case the slightest amount of water in them renders them worthless. 
The “capillary” is shown at v, and enlarged in fig. 2. It is made by 
sealing within a larger glass tube a small one first drawn out to a very 
fine capillary. With a head of 4o or 50 cm. it should allow several drops 
of alcohol to flow per minute. If the flow is too slow, the small end of 
the fine capillary may be broken off with a pair of forceps. Otherwise 
the flow is regulated by raising either the supply bottle or the remainder 
of the apparatus, which is clamped on the ring stand. As a drop of 
alcohol from v per minute means r cc. per hour, and most material may 
be dehydrated in 4o hours or less, it is easy to adjust the flow, and the 
apparatus needs no further attention until its part of the process is 
complete. B and C may each conveniently be ordinary glass tubing 
15 cm. long and 2.5 cm. in diameter. D is of similar material twice 
this diameter and 5 cm. longer. It is very convenient to have all three 
of these tubes graduated. The supply tube should be at least 6 mm. 
inside diameter, so that, when starting, the alcohol will readily replace 
the air in it; but, as the contents of the other connections are added to 
the waste alcohol and dehydration is delayed by the contents of *%, 
these should not be over 1. 5-2 mm. inside diameter. It seems that only 
the best antimony rubber tubing will withstand alcohol. Ordinary 
physicians’ catheters, one large and two small, will furnish all of this 
tubing that is needed. 
In practice it is convenient, after killing is complete, to tie the tissue 
with a label number in a square of fine silk gauze (chiffon). Knots are 
unnecessary; after the corners of the gauze are brought together a half 
dozen turns of very fine cotton thread will hold very well. A number 
of samples may then be washed very effectively under a small tap, in 
a jar the neck of which is provided with a cylinder of wire gauze as shown 
in fig. 3. After washing, the samples are transferred to the dehydrator 
and may afterward be kept in one or at least very few dishes until 
infiltrated with paraffin. The silk gauze also protects the samples trom 
the air while they are being transferred to the imbedding dish, where 
it may be cut and the pieces of tissue and label properly arranged.— 
W. A. WuLtscniecER, Nebraska Wesleyan University, Lincoln. 
