May, 1907.] 
Meetings of the Biological Club. 
LS7 
No. 10 was collected at Los Amates, Guatemala, February 
15, 1905. Length, 71 inches, tail 91 inches; gastrosteges 215, 
urosteges 65 pairs, anal plate entire. 
No. 11 was collected at Los Amates, Guatemala, February 
11, 1905. Length, 21 j inches, tail 3j inches; gastrosteges 197, 
urosteges 62 pairs. The tip of the tail of this specimen has the 
same bright green coloration that is seen in the young of the 
Copperhead (Ancistrodon contortrix) of North America. This 
specimen has also the horny point on the tail that is found in 
the adult. 
West View, Pa. 
WATERGLASS FOR MARKING SLIDES. 
Robert F. Griggs. 
As long as serial sections have been studied some method of 
marking the slides while in process of staining has been neces¬ 
sary. Very many devices have been proposed all of which have, 
so far as the writer knows, decided disadvantages. Most of 
them are either too cumbersome or the marks come off too 
easily. The following method which seems to meet all objections 
has not so far as I have found been previously suggested. 
The medium is simply waterglass, an aqueus solution of 
sodium- or potassium-silicate, thinned if necessary till it will 
flow well from a pen. The most convenient time for marking the 
slides is when they are first taken from the box, before they are 
cleaned. An ordinary steel pen of the stub or ball-pointed sort 
is used. After the slides are marked they must be heated, either 
before or after they dry, preferably by holding them for a few 
seconds in the blue cone of a bunsen flame till the waterglass 
decomposes giving off strong jets of sodium light, and at the 
same time effervescing so as to leave behind a rough sandv sur¬ 
face. This is then rubbed down by a single stroke aaginst the 
edge of the table or any hard object and leaves a ground glass 
surface which, if the fixing has been properly done, is absolutely 
permanent and will not be affected by any reagent which does 
not attack the slide itself. 
If desired some such dye as carmine may be stirred into the 
solution to make the marks more conspicuous. A whole series 
of colored inks could probably be made with a little experimenta¬ 
tion but care must be exercised in choosing colors which are 
chemically inert because of the ease with which the silicate is 
precipitated. 
This process takes no more time than sticking a paper label 
to a slide and writing the data upon it in the usual way. For 
serial slides where large numbers are made of the same material, 
