May, 1907.] Meetings of the Biological Club. 157 



No. 10 was collected at Los Amates, Guatemala, February 

 15, 1905. Length, 71 inches, tail 9^ 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 3^ 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 sandy sur- 

 face. This is then rul)bed 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 aft'ected 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, 



