The hrowninf:^ process took a diflerent course in tlie stamens. After 

 they liad heen taken out of the freezing cyHnder they remained apparently 

 unchanged, while the petals had already begun to wiU. ( )nly later did the 

 stamens become yellowish brown and the anthers a jjale \ellow. A cross- 

 section through the stamens showed that the brown coloration was essen- 

 tially conditioned by the epidermis which is rich in contents. To be sure, 

 in all the tissues, the cell contents seemed contracted into drops or lumps 

 and were brown, but the amount of substances in the inner cells was so 

 scanty that the coloring of the whole tissue remained pale. The spiral ducts 

 of the stamens, like those in the petals, had light brown walls. In the 

 anthers, the discoloration depended likew ise on the amount of cell contents. 

 These were most al)undant in the connective tissue and this consequently 

 seemed most deeply brown, while the epidermis in the antliers themselves 

 and the underlying fibre cells, arranged like palisades, had only \ery scanty, 

 solid masses of contents and, tlierefore. seemed almost colorless. The rem- 



Fis". lO.S. Cros.s- sect ion of a petal of the apple injured hy artificial frost. 



nants of the ground tissue near the connectixe tissue were somewhat 

 darker. 



The pistils showed the greatest injuries. They were a deey) brown and 

 l)ent when taken (uit of the freezing cylinder. At first no collapse of the 

 tissue could be seen anywhere. The papillae of the stigma seemed stiff and 

 filled with brown cytoi)lasmic contents. As in a fresh condition, they still 

 held fast the somewhat swollen and, therefore, differently formed pollen 

 grain.s. tilled with cloudy, uniform contents. In the pistil, as in the stamens, 

 the peripheral layers were richest in content and, therefore, their contents 

 and walls most deeply colored brown. 



Among the mechanical disturbances, tangential holes were observed 

 here and there in the tissue of the pistil as in that of the stamens. They 

 were partly produced by the loosening of the cells from one another, but 

 also by the tearing of the cells themselves. The number and ."^ize of the 

 holes in the tissue increased towards the bottom of the pubescent pistil, the 

 hairs of which. i)oor in contents, showed a browning of the walls. Here 

 the tissue at the base of the pistil widened into five diverging, bluntly conical 



