109 



in Ihe culture nicdiuni. IT Ihc lens is not cxtirpaled in the 



way described here, it nuiy happen, that fibrobhists from 



the iris will remain on the lens and the cultures will then 

 not be pure epithelium. 



TECHNIQUE FOR THE PREPARATION' OF 

 THE CULTl'RES. 



It was observed, that the epithelium grew very irregul- 

 arly at the outset. An extensive liquefaction of the i)lasma 

 occurred during the growth and after a certain amount of 

 the clot had liquefied, the growth became very extensive. 

 This fact suggested, that if we immediately could bring 

 the fragment of tissue under such conditions as had a lique- 

 faction already taken place, the result would probably be 

 an extensive and uniform growth. It was therefore essayed 

 to place the little fragment of epithelium on the free sur- 

 face of the coagulated plasma and cover it with a thin film 

 of embryonic tissue juice. The result of this arrangement 

 was very striking. — The culture medium was composed 

 of, as usual, equal volumes of embryonic tissue juice and 

 plasma from adult chickens, which are added together on 

 a coverslip and mixed. When the coagulation commenced 

 which can be ascertained with the point of the knife, the 

 tissue fragment is placed on the free surface of the nascent 

 clot. It is important to place the tissue at the proper moment; 

 if it is placed before the coagulation has commenced, it 

 will be embedded in the clot — and if it is placed too late, 

 it will not adhere, but float in the covering droplet of tis- 

 sue juice. After the fragment is properly placed, a small 

 drop of embryonic tissue juice is spread out to a thin film 

 on the clot to establish a moist surface for the proliferation 

 When transferring the culture, the fluid is removed by means 

 of a piece of steril filter paper, and the culture cut out of 

 the clot in the usual wav. 



