SCIENCE—ADVERTISEMENTS 
Spencer Microscopes 
Nos. 44 and 64 
Embody a side-fine adjustment (the critical mechan- 
ical part of any microscope) of superior type : 
I. Simplest—fewer parts—less to get out of order. 
II. 34 threads of the screw engaged as compared 
with the equivalent of but one in the others. 
III. Ithasa “lateral travel’’—an index to its posi- 
tion, relative to its limits. 
IV. It is fool-proof durable. It cannot be forced 
beyond its lmits—steel stops prevent. 
These advantages are the result of our many years of 
pioneering in side-fine adjustment construction. 
Catalog sent on application 
SPENCER LENS COMPANY 
BUFFALO, N. Y. 
“SPENCER 
| BUFFALO 
Ee 
Marine Biological Laboratory 
Wocds Hole, Mass. 
INVESTIGATION _ Facilities for reseach in Zoology, 
Embiyology, Physiology and Bot- 
Entire Year any. Seventy-six private labora- 
tories, $100 each for not over three 
months. Thirty tables are avail- 
able for beginnersi n research who 
desire to work under the direction 
of members of the staff. The fee 
for such a table is $50.00. 
Cooking Class at — 
South Dakota State College 
are using gas made by 
The “ Detroit”’ 
Combination Gas Machine 
INSTRUCTION Courses of laboratory instruction 
pil euuates ere Onened La pave 
rate Zoology, Embryology, Physi- 
July 3 Sea 13, ology and Morphology and Taxo- 
918 nomy of the Algae. Each course 
requires the full time of thestudent. 
Fee, $50. Alecture course on the 
Philosophical Aspects of Biology 
and Allied Sciences is also offered. 
for supplying gas in Departments of 
Domestic Science 
SUPPLY 
Animals and plants, preserved, liv- 
Open the Entire Year 
ing, andinembryonicstages. Pre- 
DEPARTMENT served material of all types of 
animals and of Algae, Fungi, Liver- - 
worts and Mosses furnished for 
classwork, or for the museum. Livy- 
ing matetial furnished in season 
as ordered. Price lists of Zoological 
and Botanical materia] sent on ap- 
lication. State which is desired. 
or price lists and all information 
regarding material, address 
GEO. M. GRAY, Curator, Woods Hole, Mass. 
Chemistry and Physics 
(Over 30,000 in daily use) 
Laboratory work can be done better, 
quicker and cheaper by using this gas. 
Ask for descriptive catalog and names 
of users in your vicinity. 
Detroit Heating & Lighting Co. 
612 Wight St. Detroit, Mich. 
The annua]announcement will be sent on application to The Est. 1868 
Director, Marine Biological Laboratory, Woods Hole, Mass. 
