325 



at p. These are very much elongated, extraordinarily thick-walled cells, 

 traversed by many, frequently branched canals ; they turn yellow with 

 chloriodid of zinc. Single layers of such cells may cross one another. Ac- 

 cordingly, besides such cells seen in full length at p, the same horizontal 

 section also exhibits parts of elements in cross-section q. It is evident that, 

 because of the close arrangement of the cells on the one hand and because 

 of their very strong walls on the other hand, a very great firmness is ob- 

 tained in the core tissue, increased by the transverse course of the cells. It 

 is evident further, that in fruits with a larger calyx depression, through 

 which fungi may grow easily into the core, the spread of fungi, which pro- 

 duce decay, is limited by the parchment-like, solid carpels. 



Fig. 44. 



Rupturing of the papery carjei oi the apple, due to the excrescence tis 

 of a Avoolly strealv. (Orig.) 



This protection from internal decay is destroyed by the woolly streaks 

 (Fig. 43 W) for they consist of very loose tissue, which breaks through the 

 solid walls. 



We see in Fig. 44 that these woolly streaks are formed of thick bunches 

 of cell rows elongated like threads, which differ strikingly from the sur- 

 rounding ones because of their thinner walls, and very gradually pass over 

 into the tissue of the fruit {F), while others are quite sharply and suddenly 

 cut off from the thick- walled cells (/») below the places in the core which 

 have remained membranous. Only at the base of this bunch of threads do 

 short, schlerenchymatous cells {sk), isolated or lying beside one another in 

 mats, recall the elements {p) to be found in the normal wall. Although these 



