from the inner Hesh of the fruit ( 'H ) may be seen in the transitional zone 

 from pistil to ovaries, even with a low magnification. It should he empha- 

 sized that in this, as in the stamens, a tearing of the cells (cj actually takes 

 place, while in the coarser tissues only the usual separation of the different 

 cell layers is formed. These mechanical disturbances which, as we shall 

 see later, are so im])ortant in the vegetative organs, have a lesser influence 



in the blossoming organs. The 

 inflorescences die l>ecause of 

 the chemical change in the 

 cell contents and drop more 

 (|uickly if the tissue splits at 

 the same time. The experi- 

 mental results correspond to 

 the phenomena after natural 

 spring frosts. 



The dependence of the 

 susceptibility upon the consti- 

 tution of the cell sap may be 

 ]K'rccived from the adjoining 

 illustration of a young apple 

 blossom severely frosted (Fig. 

 105 ). The shading, carried out 

 only on one side in this and 

 other drawings, holds good 

 naturally for both halves. All 

 the shaded parts indicate tis- 

 sues with intercellular spaces, 

 which clearly contain air. At 

 ;- sugar may be proved by the 

 glycerin reaction. The crosses 

 indicate the regions where 

 metal)olism has already ad- 

 vanced so far that abundant 

 calcium oxalate is deposited. 

 The rings (/) are intended to 

 indicate the different places 

 turned brown by frost ; all the 

 younger, inner parts, rich in 

 cytoplasm, have remained 

 healthy ; the dark line is a vascular bundle. 



Here we should mention only supplementarily the fact that, besides the 

 acute affects of cold already described, chronic disturbances in the life of 

 the blossoms also occur which concern only the retarding of the normal life 

 processes. The best known example might well be the suppression of the 

 opening of the blossoms in Crocus renius and TiiJipa Gesneriana. Because 



Fis. lor.. 



I'rimordia of an apple flower butl 

 injurerl by frost. 



