143 



Fig. 13. Section tlirough the leaf-stalk of a frozen artichoke. (From 

 Sachs, 1860.) Tlie hatched spaces represent the ice masses, the black spaces, 

 the cavities of the ruptured tissue. 



Prillieux (1869a) insisted on the fact that, in frozen 

 tissues, ice was found between the cells and not in them. 

 This was observed in petioles, in buds, in stems, etc. Some 

 stems presented, in a cross section, four masses of ice 

 radially distributed, some three, some five, depending on 

 their structural symmetry. A layer of ice always isolated 

 the epidermis; the pith often seemed filled with ice crys- 

 tals; the parenchyma was usually split into several por- 

 tions separated by ice masses. Since the cell walls were 

 not broken, Prillieux remarked that they could not have 

 been traversed by ice crystals and that, therefore, it was 

 in the liquid form, before freezing, that water had left the 

 cells. 



Fig. 14. Intercellular lens-shaped masses of ice in plant tissues. (From 

 W'iegand, Plant World, 9, 26, 1906.) Each mass consists of two layers of 

 ice pillars. In the middle of the tissue, (A) the pillars have the same length 

 in the two layers; they are of unequal length nearer the external surface of 

 the tissue (B) ; only one layer remains at the surface itself (C). 



