1908.] 



Diffusion into Living Cells. 



101 



which contains 1 gramme of sodium citrate and - 8 gramme of sodium 

 chloride. It is neutralised and rendered acid with - 083 gramme of citric 

 acid. It is then collected in quantities of 5 c.c. In order to determine the 

 cf of a cell, a tube of 5 c.c. is melted and certain quantities of stain and 

 standard solution of alkali added. The content of the tube is then completed 

 with water up to 10 c.c. Consequently the tube contains 1 per cent, sodium 

 citrate and - 8 per cent, sodium chloride in addition to the acid, stain, and 

 alkali, and this content of salts allows leucocytes to live on the jelly. The 

 whole is then boiled until it froths up the tube and a film prepared from it 

 by pouring a drop on a slide and allowing it to set. The cells are placed on 

 to the film and the slide is kept at a convenient temperature for a period of 

 time. If the nuclei or cytoplasm are not yet stained, a higher temperature 

 may be tried combined with a longer period of time, or a fresh tube prepared 

 with more units of alkali added, and so on until staining is obtained. Should 

 the contents of a tube cause the cells to stain very deeply, or if they soon 

 become achromatic, a fresh tube is made containing less stain, or more salts, 

 or less alkali, or acid may even be employed, and so on. But provided the 

 arrangement of the contents of the tube which just causes staining of the 

 nuclei is known, and if the time and temperature are also known, the 

 equation will give the cf required. 



Units. — In preparing these units I have mainly considered their practical 

 application in the endeavour to curtail the procedure as much as possible. 

 In the instance of alkali and salts, I give the actual amount in grammes 

 which 10 c.c. of jelly should contain as 1 unit. I also give a convenient 

 standard solution and the amount of it in cubic centimetres to be contained 

 in the 10 c.c. of jelly to constitute 1 unit. 



Alkali, Sodium Bicarbonate, hastens diffusion. — Unit, - 005 gramme. 

 Standard solution 5 per cent., unity being 0*1 c.c. It is convenient to 

 remember that this solution is neutralised by a 4 - 175-per-cent. solution of 

 citric acid, and that 1 unit of alkali is neutralised by 0'1 c.c. of such 

 a solution. Since the agar at the outset is acid to the extent of 

 - 083 gramme to 50 c.c, a tube of 10 c.c, made up as described, must 

 contain 0"0083 gramme of acid. This is exactly neutralised by 0*2 c.c of 

 the standard alkali solution ; that is, the agar at the outset, before any stain 

 or other factor is added, delays diffusion to the extent of 2 units. Or, the 

 addition of 2 units of sodium bicarbonate will render the agar neutral. 



Sodium Citrate, delays diffusion. — Unit - 03 gramme. Standard solution 

 10 per cent., 0'3 c.c. being unity. Since 50 c.c. of agar contains 1 gramme at 

 the outset, the 10 c.c of jelly may be said to contain about 3 units. 



Sodium Chloride, delays diffusion. Unit - 08 gramme. Standard solution 



