Slock Solulio7is 409 



To make a normal solution, add to the ml. in the right-hand column 

 enough distilled water to make a combined total of 1 liter. This will be 

 accurate enough for histological preparations. 



Stock Solutions 



The solutions included under this title are probably found (with a 

 few exceptions) on most histology laboratory shelves. 



Three physiological solutions are included to offer a choice, depend- 

 ing on the particular need of the type of research in progress. The use 

 of physiological solutions can be imperative at times. A normal solution 

 (isotonic) contains the proper amoimt of salts to maintain tissues in a 

 normal condition. For instance, red blood cells will remain unaltered 

 in form and will not experience a loss of hemoglobin if isotonic fluids 

 are used with the cells. The osmotic pressure and salt content of the 

 physiological solution and of the blood fluid is the same. If the sokuion 

 is hypotonic, the osmotic pressure and salt content is less than that of 

 the body fltiids and the cells will swell. If the solution is hypertonic, 

 the osmotic pressure and salt content is greater than that of the body 

 fluids, and the cells will shrink. Plain distilled water will be hypotonic 

 until the proper quantity of salt has been added. 



Just as physiological solutions are useful for land vertebrates, so are 

 environmental solutions convenient for some invertebrates. In the case 

 of marine invertebrates, such solutions can become necessary for success- 

 ful preparations and sometimes are recommended as the basic fluid for 

 fixing solutions. Among the physical properties of sea water, the salt 

 content has to be considered. It varies and is complex, but an arbitrary 

 definition of salt content (salinity) has been calculated. Salinity (S 0/00) 

 equals the weight in grams (i7i vacuo) of solids in I kilogram of sea 

 water. The major constituent, which is easily determined, is silver- 

 precipitating halides. Chlorinity (CI 0/00) is defined as the weight in 

 grams (in vacuo) of chlorides in 1 kilogram of sea water. Standard sea 

 water is about 19.4 0/00 chlorinity and 34.3243 0/00 salinity. (Barnes, 

 1934) 



Not all of the adhesive or buffer solutions will be found or required 

 in every laboratory: however, a listing of the more widely used ones 

 seems practical. Then if a need should arise, the information is at hand. 



Stain solubilities are only occasionally useful, but they are definitely 

 needed when a saturated solution must be made. 



