198 THE AMERICAN MONTHLY [June 



arc lamp may be so regulated by hand that by reference to 

 cross-wires on a glass screen, the source of light may al- 

 ways be kept in the same place. A small area of great in- 

 tensity is obtainable by setting the carbons in an oblique 

 position. 



MICROSCOPICAL MANIPULATION. 



Red Stain. — The haemoglobin granules in the lamprey, 

 frog, hens and guinea pigs may be made visible by use of 

 saturated solution of neutral red in 0.8 per cent sodium 

 chloride. 



Preservative. — Alcohol decolorizes sponge specimens 

 but a solution of formalin-glycerine will not. Use three 

 parts pure glycerine to two parts of a 3 per cent formalin. 



Examination of Steel. — The structural character can be 

 shown by mounting specimens ^inch in diameter on a slip. 

 Grind down the surface on oil stone, then on a Belgian oil- 

 hone, then polish on chamois leather stretched over a block 

 of wood charged with peroxide of tin. Do not use emery, 

 a crocus paper, range or wheels charged with any cutting 

 powders. 



BIOLOGICAL NOTES. 



The Marine Biological Laboratory At Wood's Holl. — 

 The Twelfth Session of the Marine Biological Laboratory 

 will begin on June 1st, and will continue for four months. 

 This session promises to be the most successful in the 

 history of the Laboratory. The courses of instruction 

 heretofore offered will be maintained by an exceptionally 

 strong staff, and three entirely new courses have been 

 added, including Micro-chemistry. There will be : 

 A Course of Lectures on Plant Morphology and Phy- 

 siology. 



First Week, July 5-12.— Erwin F. Smith, 'Bacteria'; D. 

 T. MacDougal, 'Physiological Subjects'; Douglas H. Camp- 

 bell, 'The Evolution of the Sporophyte in the Archegoni- 



