68 MONTROSE T. BURROWS 



oxalate was made up in Ringer's solution which contained the 

 desired lower concentration of sodium chloride. One part of this 

 solution precipitated the sodium oxalate in nine parts of the blood 

 plasma. 



In the first series of preparations of thirty-five specimens, eleven 

 showed active growth of mesenchyme cells for the first forty-eight 

 houis. Magnesium was added in various concentration in the 

 next series, one part in fifteen thousand proving most satisfactory. 

 In all specimens of this series, forty-three in number, marked cell- 

 ular activity of mesenchyme elements was noted throughout 

 the first forty-eight hours (fig. 2). After this time, all showed 

 degeneration and death. The addition of magnesium in this series 

 gave marked increase in the number of specimens developing in 

 oxalated plasma, but no increase in the duration of growth. Sub- 

 sequent control series gave the same results. When aqueous 

 extracts of the area vasculosa, together with ether-soluble bodies 

 of the yolk, were added to this plasma in small quantities, an 

 increase in duration of growth was the result. The specimens of 

 this type showed a period of growth extending over seventy-two 

 hours, but no nerve fibies developed in these preparations. 



Pure plasma. The use of a pure plasma has given far better 

 results. In this medium, the growth was prolonged for a number 

 of days with marked activity of both the mesenchymatous and 

 epithelial tissues. In the following descriptions, only specimens 

 grown in this medium have been used. 



The method of preparation of pure plasma has been in part 

 similar to that used by Delezenne ('97) . The blood was obtained 

 from young health}^ chickens by ordinary operative procedure. 

 Ether was used as an anaesthetic. The carotid artery was exposed 

 and a canula, previously sterilized in pure olive oil, was inserted, 

 necessary precautions being taken against contamination of the 

 blood by the tissues (Delezenne). The blood was collected in 

 thick-walled paraffin-coated tubes and quickly cooled by placing 

 the tubes in an ice-salt bath. The tubes were centrifugalized at 

 once by placing them in a large centrifuge tube filled with ice and 

 salt. The supernatant plasma was then removed with a paraffin- 

 coated pipette to another tube and placed in a refrigerator until 

 ready for use. Plasma may be obtained by this method in a very 



