1903 Anszvers to Correspondents 91 



Mr Carleton Rca writes concerning this photo, which is reproduced 

 at p. 52 of this issue: "The photograph represents a birch-tree with 

 several pilei of the parasitic Polyporus hcttilimts, Fr. This species is 

 confined to birch, and is only too common in our woods. It is a wound 

 parasite, and ultimately causes the death of the tree. It entirely 

 destroys the wood, where it penetrates lignified cell walls, sieve tubes, 

 bast rind, and even the stone cells. The flesh of this parasite is some- 

 times cut up into strips and utilised as razor-strops, and micro-lepidop- 

 terists often use it in place of cork for pinning on their fragile silver 

 pins." 



Answers to Correspondents. 



J. G., Southport. 



The shore outline is changing rapidly in various places, in some 

 being added to, in others being washed away. The promontory of 

 Dungeness, Kent, has grown for two hundred years at the rate of 36 

 feet a-year. The sandstone island of Heligoland is a mere fraction of 

 its former size ; probably only a quarter is left. At Bideford Bay, where 

 Westward Ho stands, the sea has removed the land recently at the 

 rate of 30 feet a-year. See Prof. Cole's ' Open-Air Studies ' for many 

 similar examples. 



H. M., Bath. 



The Potato disease is due to a fungus producing whitish spots on 

 the under-sides of the leaves. Threads penetrate in all directions 

 through the tissues of leaves and stalks, feeding on the cell material 

 and attacking the tubers. See ' Nature Studies' (Scott Elliot). 



Codlin, Worcester. 



The Codlin Moth, a small grey insect, lays the egg in the centre of 

 the withering flower ; the caterpillar developing from this eats down to 

 the core, destroying the seeds, and emerging through the flesh of the 

 apple. It then hides in the bark during the chrysalis stage, coming 

 out the next spring as a full-grown Codlin Moth. 



Agnes, Chichester. 



The peel of the fruit contains oily matter which serves as a protec- 

 tion for the soluble substances in the flesh, notably the sugar. 



A. F. G., Grimsby. 



The Soldier Crab dwells in a whelk-shell, discarding a small one for 

 a larger as required. 



