494 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Some are useful for temporary slides, while in others the intricacy of 
the process greatly increases the chance of error, and adds to the time 
required for the work. 
There are no methods given in Lee’s work of an earlier date than 
1880. One of the oldest is the shellac method, now no longer used. 
Schallibaum’s collodion also is best fitted for bulk-stained objects. A 
slide is coated with a thin even layer of one part of collodion to three 
>r four volumes of clove or lavender oil. The sections are arranged 
and the slides heated over a water-bath for five to ten minutes, or over a 
lamp for a shorter time, till the oil has evaporated. Gage and Summers 
use a pure collodion coat on the slide which is rendered adhesive by 
clove oil or ether-alcohol. There are many gum methods, but some 
forbid the use of watery fluids, and others are not fitted for alkaline 
stains. 
Lee recommends Mayer’s albumen for use with sections that have to 
be stained on the slide, and says that he has found it to be absolutely 
reliable. There is no need to describe so well known a method, the 
principle is the coagulation of a thin layer of albumen by the use of 
heat. It is just at this point that the element of uncertainty comes into 
the process; much heat will injure the tissue, and in avoiding this 
danger there is a great probability of applying too little heat to co- 
agulate the albumen. 
Among other methods given by Lee is one recommended by Strasser.* 
It consists of coating the slides thinly and evenly with a mixture of two 
parts of collodion with one of castor oil — the percentage of the collodion 
is not given. Sections are arranged on those prepared slides and coated 
with a thicker solution — collodion concentratum duplex, 2-3 parts ; 
castor oil, 2 parts ; no warming is required, but the slide is put direct 
into a bath of turpentine for two to ten hours to dissolve out the 
paraffin. 
While working during the past year with serial sections, great 
trouble was experienced with Mayer’s albumen method, and after some 
experimentation, the following plan was adopted. A layer of Mayer’s 
albumen was spread on the slide and the sections arranged. Then a 
wash of % per cent, collodion was spread over the surface evenly with a 
camel’s hair brush. This coat is allowed to dry, which takes place in 
about one minute, but a longer time does no harm; practically, one 
slide dries while the next is being prepared. During the drying many 
small air bubbles appear, the presence of which indicates the right 
degree of dryness ; these do not cause any inconvenience, as they dis- 
appear during the subsequent processes. When dry the slide is put, 
without heating , into a jar of xylol or benzin for half an hour or more, to 
dissolve the paraffin. A stay of several hours in the liquid will not 
injure the tissue. The paraffin may be removed in three to five minutes 
by constantly moving the slide in the benzin. The benzin or xylol is 
removed by 95 per cent, alcohol, and the sections are then stained and 
mounted as desired. 
It was found best to have the liquid for removing the paraffin as 
fresh as possible, or else the thin film of collodion retained a sufficient 
amount of it to render the surface greasy ; benzin was tried, and proved 
* Zeitschr. f. wiss. Mikr., iv. I. (1887) p. 45. 
