THE CULTIVATION OF TRYPANOSOMES IN VIVO. 



313 



When a rat is to be injected intraperitoneally, the skin on the back of the 

 neck or shoulders is seized with a pair of self-locking rat forceps. The tail 

 and hind legs are pulled well down and held in the left hand, along with the 

 forceps. The needle, held in the right hand, is inserted thru the skin and 

 muscular wall in the median portion of the abdomen and the desired amount 

 of the contents of the syringe injected. In making a subcutaneous injection 

 the rat is held in the same manner, the needle being inserted just thru the 

 skin in the thoracic region. Guinea; pigs do not offer the vicious resistance 

 to this treatment which is characteristic of rats, and consequently it is not 

 necessary to handle them with forceps. When making a subcutaneous in- 

 jection it is advisable to lift the point of the needle slightly after it has been 

 inserted, in order to determine definitely that it has not entered the muscular 

 tissue. 



Beginning with the next day or the second day after an animal is injected, 

 daily or bi-dail.y examinations of its blood are made. A drop of blood is ob- 

 tained in the manner described above, but instead of being taken into a 

 syringe, is touched to a clean glass slide and immediately covered with a 

 clean eoverglass. The cover-glass is pressed down until a layer of blood of 

 about the thickness of one red blood corpuscle remains under it. Care is taken 

 not to push the eoverglass sidewise as this causes rapid plasmolysis of the 

 red cells. This "fresh preparation" of the blood is examined under the 4mm. 

 objective with a No. 10 ocular and 160 mm. tube length, and the number of 

 trypanosomes per field is counted and recorded. 



The following method of keeping the records of the animals and cultures 

 has proven most satisfactory. The inoculated animals are kept in battery 

 jars or small wire cages which are marked with gummed labels bearing the 

 following information: the name of the organism, the number of the animal, 

 the page in the note-book on wtiich its record can be found, the date of inocula- 

 tion and any mark that may be necessary to properly identify the animal in 

 question. The latter item is only used when two or more animals are kept 

 in the same jar or cage. For example: 



This label shows that this animal was inocula- 

 ted with Trypanosoma Brucei on Februai-y l,and 

 that it is number eight on page two of the note- 

 book. The 'L' indicates a notch cut in the left 

 ear to distinguish it from another animal in the 

 same cage. On page two, the following record of 

 this animal is to be found : 

 1-5-17 — 0.5 per drop. 

 1-8-17—1-100 pf. 

 1-13-17—2 pf. 



1-15-17 — 5 pf M ear drop to 7p2. 

 1-17-17—10 pf. 

 1-20-17-0 pf. 



Typanosoma 



Brucei. 

 8p2 



L 

 2-1-17 



6. Blk. and Wht. 

 G. pig. M ear drop 

 from 5p2. Sub cut. 

 inj. 



1-2-17 



