30 THE AMERICAN MONTHLY [Feb 



with freezing- microtome, fix sections in 4 per cent forma- 

 lin sol. 3-5 minutes, absolute alcohol 1 minute. Stain and 

 mount. 



Redondo Beach Diatoms. — In a bluff on the beach 10- 

 25 miles south of Santa Monica, Cal., exists one of the 

 finest deposits yet known. The foot of the cliff is accessi- 

 ble only at low tide, when pieces broken off by the waves 

 can be picked up. Tidal refuse has been carried as far as 

 Santa Monica where the diatoms were first found in 1878. 

 This material contains a great variety of diatoms which 

 are listed in Bull. Torrey Bot. Club, Nov. 1897, by E. A. 

 Schultze and C.H. Kain. Can they or our California friends 

 give us some of this earth for distribution to subscribers? 

 We shall see. 



Laboratory Dish. — An invention of Dr. Coplin of Jeffer 

 son Medical College is figured in Science, Sept. 24, 1897. 

 In taking slides through various reag-ents, the section is 

 liable to be scratched or destroyed by coming in contact 

 with other slides. This dish is provided with grooves into 

 which the slides can be set and so kept apart. Economy 

 of reagents, absence of evaporation and solidity are also 

 claimed for the invention. 



Examination of Suspected Documents. — Blares, in an 

 article on this subject, in the Journal de Pharmacie, recom- 

 mends the use of two liquids with which he moistens the 

 places on the documents at which it is suspected that a 

 forgery has been committed. The first of these liquids 

 consists of 1 part of castor oil dissolved in 6 parts of alco- 

 hol of 95 per cent. This is painted on with a camel's hair 

 pencil, the effect being to make the paper partially trans- 

 parent, and thus to bring out traces of erased writing. 

 The second application consists of 2 percent aqueous solu- 

 tion of caustic soda. The operation of this liquid depends 

 upon the methods of the falsificator. As a general thing-, 

 the latter removes a single figure from a number. In order 

 to bring back the horizontal line, a portion of which he 

 must almost necessarily remove, and to repair any damag-e 

 done to the surface by the process of scraping or shaving-, 



