CHINESE INK PREPARATION 85 



2. Using the sterile toothpick, make five rows of small 

 droplets (five droplets in a row) on a sterile cover-glass and 

 place, culture side down, over the concavity of a sterile slide. 



3. Seal the cover-glass with paraffin as in the prepara- 

 tion of the adhesion culture. Examine microscopically. 



4. Locate one droplet which contains only one cell. 

 Using India ink, write the location of this droplet on the 

 slide. 



5. Make a drawing of each stage of development until 

 growth ceases. Why does the cell stop growing? 



6. State in detail your results with any conclusions 

 to be drawn a*nd point out the practical applications which 

 may be made. 



This method may be used to advantage with mold 

 spores. 



EXERCISE 27. CHINESE INK PREPARATION 



Chinese ink may be used to make bacteria more easily 

 visible microscopically and to aid in taking correct measure- 

 ments. 



Apparatus. Sterile, dilute Chinese ink; * clean flamed 

 glass slides. 



Cultures. Pure cultures (young agar streaks are best). 



Method. 1. Place one loopful of distilled water and 

 three loopfuls of sterile Chinese ink in a row on a clean 

 glass slide, about 2 cm. apart. 



2. Inoculate the loopful of water from the original 

 culture. 



3. Distribute the organisms well with a platinum 

 needle. 



4. Then inoculate the adjoining drop of ink from the loop- 

 ful of water, the second drop of ink from the first, etc. 



6. Stir each loopful of ink well and then spread it so as 

 to cover an area about 1 cm. square. 



* See appendix for method of preparation. 



