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 t£ie others. 



III. It has a "lateral travel" — an index to its posi- 

 tion, relative to its limits. 



IV. It is fool-proof durable. It cannot be forced 



beyond its limits — 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 fglig 



BUFFALO, N. Y. 



Marine Biological Laboratory 



Woods Hole, Mass. 



INVESTIGATION 



Entire Year 



INSTRUCTION 



July 3 to Ausuftt 13. 



1918 



Facilities for reseach in Zoology, 

 Embi-yology,Phyaiology and Bot- 

 any. Seventy-six private labora- 

 tories, SlOO each for not over three 

 months. Thirty tables are avail- 

 able for beginners i n research who 

 desire to work under the direction 

 of members of the staff. The fee 

 for such a table is $50.00. 



Courses of laboratory instiuction 

 with lectures are offered in Inverte- 

 brate Zoology, Embryology, Physi- 

 <^ogy and Morphology and Taxo- 

 nomy of the Algae. Each course 

 requires the full time of the student. 

 Fee, $50. Alecture course on the 

 Philosophical Aspects of Biology 

 and Allied Sciences is also offered. 



SUPPLY 



DEPARTMENT 



Open the Entire Year 



Animals and plants, preserved, liv- 

 i ng, and i n embryonic stages. Pre- 

 served material of all types of 

 animals and of Algae, Fungi, Liver- 

 worts and Mosses furnished for 

 dasswork, oi for the museum. Liv- 

 ing mateiial furnished in season 

 as ordered. Price lists of Zoological 

 and Botanical materia 1 sent on ap- 

 plication. State which is desired. 

 For price lists and all information 

 regarding material, address 



GEO. M. GRAY, Curator, Woods Hole, Mass. 

 The annua 1 annoimcement will be sent on application to The 

 Director, Marine Biological Laboratory, Woods Hole, Mass. 



GAS-GAS 



The "Detroit" 

 Combination Gas Machine 



Automatically makes the best 

 and cheapest gas for 



Laboratory Uses of Every Character 



Heating — Cooking — Lighting 

 Over 30,000 in daily use 



catalaiut and I 

 locality sent 



imta of users in your 

 n request 



The Detroit heating & 



LIGHTING Co. 



612 Wight St. Detroit, Mich. 



Established 1868 



