110 THE AMERICAN MONTHLY [June, 



known as the stroma. A lighter-colored nucleus was distinctly visible in 

 each, which, though faint at first, became gradually more distinct. Another 

 drop of blood being treated with magenta stain exhibited the presence of the 

 nuclei in the corpuscles much more distinctly. In a red corpuscle the peri- 

 nuclear portion was scarcely aflected, whilst the nucleus was stained a deep 

 red and revealed a still darker portion within the nucleolus, and each red 

 corpuscle was evidently limited by a thin firmer membrane or envelope. 

 The white corpuscles were stained more uniformly, but the nucleus was 

 much more distinct than before staining, and in some cases was seen to be 

 two or three partite. When treated with dilute solutions of hydrochloric 

 acid and acetic acid, the red corpuscles became much more transparent and 

 colorless, the nuclei darker and more definite, presenting a beaded outline, 

 and, with careful observation, a distinctly fibrillar structure was visible, the 

 appearance being somewhat similar to that previously observed in the nuclei 

 of young vegetable cells. 



In the case of the specimen treated with hydrochloric acid, rupture of the 

 limiting envelope took place in many of the corpuscles, the h^maglobin es- 

 caping into the surrounding liquid, showing the residual stroma in the form of 

 bands extending from the nucleus to the limiting membrane. 



When a sack or bag made of an animal or vegetable membrane, and 

 containing a liquid, is immersed in another liquid of difierent density, it is 

 well-known that the liquids tend to diffuse into each other through the mem- 

 brane, and as usually the liquid of less density passes more rapidly through 

 the membrane than the one of greater density, the bag may become swollen 

 or may shrink according to the nature of the liquid it contains. A red blood 

 corpuscle represents such a microscopic sack, so that when a drop of water 

 was added to the blood under examination, the water passing into the cor- 

 puscles more rapidly than the hfemaglobin passed out caused them to swell, 

 and thus lose their oval outline and become globular, this passage inwards 

 of a liquid to an animal cell being known as endosmosis. Upon adding a 

 strong solution of sugar to another drop of blood the reverse action took place. 

 The htemaglobin was now seen to pass out into the liquid niore rapidly than 

 the svrup passed in. causing the corpuscles to shrink or collapse and present 

 the appearance of a misshapen sack. The process is known as exosmosis. 

 These latter experiments are of value in demonstrating the laws of osmosis, 

 by which the various liquids diffuse themselves through the tissues, both of 

 animals and of plants, and are also interesting to the practical microscopist 

 by showing why it is that for microscopic examination animal and vegetable 

 tissues should be mounted in ffuids as nearly as possible of the same density as 

 the liquids that surrounded them in their living state, if the cells are to preserve 

 their true form and appearance. 



In the next demonstration of the systematic course it is proposed to pro- 

 ceed with the examination of the blood of birds and of mammals, including 

 human blood ; after which the microscopic examination of the chemistry and 

 physics of the vegetable cell will be undertaken. 



REPORTS OF RECENT ARTICLES. 



The waters of New York harbor. — Dr. J. J. Kinyoun, Assistant Sur- 

 geon United States Marine Hospital Service,' has recently made a careful 

 examination of the waters of New York harbor, showing conclusively that 

 the germs of cholera and many other infectious diseases are capable of living 

 and multiplying indefinitely therein. 



