Cambridge Rocking Microtomes 
“THE ROCKER” 
is a simple, 
rigid, indestructible 
instrument of 
moderate cost* 
Many hundreds 
are now in constant 
use. 
Farther particulars are contained in 
our list No. E 182, which will be sent on request. 
THE CAMBRIDGE AND PAUL INSTRUMENT CO., LTD. 
Work ■ 
London 
and 
Cambridge. 
Head Office 
and 
Showrooms : 
45 Grosvenor Place, 
London, S.W.l. 
Annual Subscription, 
Town or Country, 
from One Guinea, 
according to number of 
volumes required 
at one time. 
SCIENTIFIC LITERATURE. 
H. K. LEWIS & CO. Ltd., Scientific Booksellers, 136 Gower St. & 24 Gower Place, London, W.C.l 
MICROSCOPES CAMERAS ACCESSORIES 
New and secondhand,' latest models, largest selection in London 
Personal inspection invited as stock is constantly changing 
DOLLOND 
Govt. Opticians 
Estabd. nearly Two Centuries 
Dollond’s will BUY for cash or accept in EXCHANGE for other goods 
which will be sent on seven days’ APPROVAL. You may purchase by 
EASY PAYMENTS if desired. Write for our Bargain List— hundreds 
of Instruments to select from. It is worth perusal — is sent gratis — and 
WILL SAVE YOU FROM 25 TO 50 PER CENT. 
Dollond’s pay high prices for first-grade modem Instruments 
211 OXFORD ST. 
61 Brompton Road, S.W. 
2 Northumberland Avenue 
35 LUDGATE HILL 
10 Old Broad Street. E.C.2 
12 George Street, Croydon 
