730 HISTOLOGIC TECHNIC 



several changes of absolute alcohol to remove the fixing fluid and com- 

 plete the dehydration. 



This fluid is especially valuable for the fixation of lung tissue. It 

 can be advantageously applied only to perfectly fresh, viz., living tissues. 



Gilson discovered that this fluid could be advantageously modified 

 for cytologic purposes by saturation with mercury bichlorid. About 20 

 grams should be added to the above mixture. As thus modified the 

 solution is commonly known as Carnoy's fluid, No. II. Its penetrating 

 properties are very high and the degree of fixation delicate. Tissues 

 should not be left in the fluid for more than an hour. The after- 

 treatment is the same as with the simple solution, except that tincture of 

 iodin must be used with the alcohols. 



Gilson 's Fluid (Mer euro-nitric mixture) : 



Bichlorid of mercury 5 grm. 



Nitric acid (approximately 80 per cent.) 4 c.c. 



Glacial acetic acid 1 c.c. 



Alcohol (70 per cent.) 25 c.c. 



Distilled water 250 c.c. 



Fix small pieces of tissue from three to twelve hours, transfer 

 directly to 70 per cent, alcohol, and pass through the higher grades, 

 with the addition of tincture of iodin. This fluid has a high degree 

 of penetration, and produces faithful and delicate fixation. 



Heat. This is a useful agent for the fixation of blood, marrow 

 cells, and scrapings from glandular and other organs, which are not 

 to be afterward stained with methylene blue or its compounds. For 

 this purpose smears made upon glass slides or cover glasses are quickly 

 dried in the air, heated to 110 degrees C. for twenty to thirty minutes, 

 and are then ready for immediate staining. 



The smears are made in the following manner: Slides or cover 

 glasses should be thoroughly cleaned with a final rinsing in equal parts of 

 absolute alcohol and ether. A small drop of blood or other fluid is 

 collected by quickly touching the center of a cover glass to a drop of 

 ordinary size. This cover glass is then immediately dropped upon the 

 surface of a second one, and the two are drawn apart by a rapid sliding 

 motion, the two surfaces being maintained parallel to one another during 

 the motion. The success of the maneuver depends upon its rapidity, and 

 to obtain very thin preparations some little dexterity is required. 



Fairly good smears are more easily made with slides. A drop of blood 

 is collected upon the end of one glass slide whose edge must have been 



