862 SUMMARY OF CURRENT RESEARCHES RELATING TO 
of the forefinger. Another improvement consists in making the receiver 
of transparent celluloid instead of horn, so that the quantity of mercury 
can be observed. In order to adapt a glass canula to the nose-piece of 
the cock, the author winds round the end a thin layer of cotton-wool 
saturated in silicate of soda solution (soluble glass), and then screws 
this in and out of the nozzle of the nose-piece, thus imparting to it a 
screw turn. After being allowed to dry for 24 hours, wax is dropped 
on the screw, so that the junction is made perfectly tight. 
Fin. 74. 
Staining by Preoccupation and Subtraction.*— Dr. P. G. Unna 
claims that Heidenhain’s method of subtractive staining and his own, 
which he calls staining by preoccupation, are substantially the same. 
Heidenhain’s method consisted in previously saturating the affinity 
of the protoplasm and nucleus with Bordeaux E, and then staining the 
* Zeitschr. f. wiss. Mikr., xii. (1896) pp. 454-7. 
