S)U 



thai th(\v (1(» iiol increase Ihc alkalinily of the fluids. The 

 (lislilk'd walcr is rcdisstilled in Pyrex or Jena glassware. 

 The |)ij)elles air made of alkali free <ilass. Mica is used 

 instead of e()vc'i"<*lass. It is iinporlani now and then lo test 

 the hydrof.;('n ion eoneenlration of Ihc watci-. Hingei's solu- 

 tion, of the tissue juices, and so on. 



PREPARATION OF Till: CTITI'RES. 



It is iin|)oiianl lo use calibrated i)i|)elles for measuring 

 the di'ops of plasma and tissue juice. It is absolutely neces- 

 sary, in ordei' to obtain coniijarable results, lo use culture 

 media of the same volume and same composition and allow 

 the medium to occupy the same area on the coverglass. The 

 growth varies much when the clot is of different thickness, 

 firstly owing to the oxygen tension, and also due to the me- 

 chanical structure of the fibrin meshwork. To obtain clots 

 with the same area, one can place the coverglass on a piece 

 of paper on which a circle has been traced, or trace a 

 circle on the mica if mica is used. After the plasma is 

 dropper^ on the glass, it is spread out with the point of 

 a knife in such a way thai it covers the circle made on the 

 paper. When the volumes of the media are the same and 

 when the area which the fluid is allowed to lake is constant, 

 the thickness of the clot will be the same and the oxygen 

 tension will be the same for (he tissues in all cultures. The 

 capacity of the hollow slides must also be identical. If one 

 is larger the evapoi'alion is greater and changes in con- 

 centration of the media occur. If one has to make experi- 

 ments as lo what effect, for instance, the dilution of the tis- 

 sue juice has on the rale of growth, care must be taken lo 

 have all conditions the same as the one which is to be ex- 

 amined. If the influence of various substances on the rate 

 of growth has to be tried and these added lo the experimen- 

 tal culture il is necessary to com|iensate the dilution of the 

 experimental culture by diluting also the culture medium 

 of the control with Ringer or Tyrodc solution in i)roporli()ii. 



