CHICKEN BONE MARROW IN PLASMA MEDIUM 77 



TECHNIQUE OF CULTIVATING, PRESERVING, AND STAINING BONE 



MARROW 



It is not necessary to describe in detail the technique of these 

 cultures, since the writer followed the same methods as those 

 used by Harrison ('10), Burrows ('11), and particularly Foot 

 ('12 and '13). For storing the plasma it was deemed important 

 to use the methods described by Walton ('12) for keeping mam- 

 malian plasma in good condition for long periods of time. Great 

 stress was laid on the study of the living cells, and a warm stage 

 was used to follow out the transitions of one cell form into 

 another. The bone marrow of very young chickens, those of 

 medium age, and of old individuals was studied; observations 

 were also made on bone marrow which contained a very small 

 amount of fat, as well as that which had a large amount of fat. 



The method described below gave the best results in identify- 

 ing and showing the stages of the individual cell types in stained 

 preparations. A small particle of bone marrow was put into 

 the plasma medium. The cells in the tissue were then allowed 

 to migrate out of it. At periods of either 2, 4, 6, 12, or 24 hours, 

 the original particle of bone marrow was extracted, and the fate 

 of those cells which had emigrated was studied. The writer 

 found that from the original particle of tissue numerous cell- 

 forms had been sent into the surrounding plasma clot. Having 

 thus extracted the bone marrow, it could be determined with 

 absolute exactitude which cell-forms emigrated first, and the 

 history of those cell types which had emigrated after 2, 4, 6, 12, 

 or 24 hours, or at any given period, could be recorded. The 

 extracted particle of bone marrow was now transferred to a new 

 plasma medium and the cell forms which emigrated after the 

 transfer were also observed. This was repeated several times, 

 until practically all emigration of cells into the surrounding 

 plasma had ceased. The structure of the remaining particle of 

 bone marrow was of course studied. Smears and sections were 

 made at every stage of the emigration process and a more com- 

 plete history of this complicated process was thus obtained. 



In staining the pieces of bone marrow, the methods used by 

 Foot in 1912 and 1913 were followed and other methods for the 



