183 



velocities lluui lliosc obtained with dead matci-ial. 27. 

 There is little evidence of a eiitectic freezing- in tissues. 

 28. The quantity of ice formed per unit of time decreases 

 gradually, in the course of freezing. 



29. In colloids and in tissues some ice formation has 

 still been observed below -20°. 30. It took 26 days, at 

 - 11°, for the completion of crystallization in a gelatin gel. 



31. The following properties of ice are discussed : i^las- 

 ticity, fluidity of single crystals, viscosity, tensile strength, 

 compressibility, suppoi'ting force ; specific gravity ; specific 

 heat, heat conductivity, heat of fusion, heat of evaporation, 

 vapor pressure, coefficient of expansion; electrical resis- 

 tance, specific inductive capacity ; birefringence, refractive 

 indices. 



32. The melting curves of tissues differ from the freez- 

 ing curves in particular by the position of the melting point 

 and by the "curve-area" representing the quantity of heat 

 involved in each of the two processes. 



33. After freezing and thawing, some colloids stay unal- 

 tered while others are irreversibly precipitated. 34. The 

 causes of precipitation assumed by various investigators 

 are: a compression between the ice masses, a change in 

 electric charge during freezing or thawing, a change in 

 chemical structure and the reaching of the saturation tem- 

 perature. 35. Alterations of tissues by freezing include: 

 changes in external appearance, release of enzymes, inter- 

 nal chemical changes, disaggregation of cellular constitu- 

 ents, and protoplasmic precipitation. 36. The latter seems 

 to be of different nature than coagulation by other lethal 

 agents. 



