OUTLINE POR LABORATORY STUDY OF THE CHICK 347 



Similar sections in green bone may be studied if prepared as 

 follows. Secure specimen of bone just removed from a fowl and 

 place it for three days in a 10 per cent, aqueous solution of hydro- 

 chloric acid. Test by puncturing with a needle, and, if all the 

 mineral salts are removed, place in a water bath and wash for four 

 hours. Pass it through the fluids usually employed in preparing 

 specimens for sectioning with the microtome. Stain as sections of 

 other tissue for microscopic study. See the description below. If 

 the ends of the bone be included, it will enable the student to study 

 not only compact bone but also cancellated bone and articular, or 

 hyaline cartilage, and in some of the bones, as the femur, the red 

 marrow. 



Special Technic for the Dissection of Cranial and Spinal Nerves. — 

 It is rather difficult to dissect the cranial and spinal nerves of the 

 fowl, owing to the fact that the structures are very small. The 

 bone is rather hard and the nerve tissue so delicate that great skill 

 must be attained to achieve any degree of success. 



A simple technic has been developed as follows: Place the head 

 and neck, or other structures of the spinal column in a 10 per cent, 

 aqueous solution of hydrochloric acid for three or more days, the 

 time depending on the size of the specimen and the amount of soft 

 structures surrounding it. This solution removes all the calcium 

 salts from the bone and makes the removal of the bony structures 

 a less difficult task. 



Directions for the Study of Soft Structures. — Secure a specimen of 

 the tissue to be studied — limg, muscle, intestine, hver, pancreas — 

 from a normal fowl just killed. The specimen should be not more 

 than y% Jnch square. After first hardening three days in 10 per 

 cent, formaldehyde. Pass through the following fluids: 



±. Alcohol, 9S per cent 24 hours 



2. Alcohol, absolute 24 hours 



3. Alcohol and ether, equal parts 24 hours 



4. I per cent. ceUoidin , 24 hours 



5. -> per cent. ceUoidin 24 hours 



6. 4 per cent, celloidin 24 hours 



7. 6 per cent. ceUoidin 24 hours] 



8. 10 per cent. ceUoidin 24 hours 



9. Place on block, and as soon as soUd, place in 80 per cent, alcohol 

 untU ready to section. Histoloid or parlodion wiU take the place 

 of ceUoidin. 



