150 Vaizey . — On the Absorption 
cell-walls of the peripheral tissues have undergone some 
change, which, if not actual lignification, appears to be a 
change of that nature, both from the fact that water is easily 
absorbed by the walls and also because they are turned 
yellow by iodized zinc-chloride and by aniline chloride. 
If now we turn to the sporogonium of the Moss, the 
condition of the cell-walls is found to be very different from 
that of the stem and leaves of the oophyte. In the first 
place the surface of the seta, apophysis, and sporangium is 
smooth and glistening and will not absorb water ; the 
foot is the only exception. A number of experiments on 
sections of the different parts of the sporogonium have given 
the following results, Polytrichum commune still being used. 
Transverse sections of seta : — 
Iodized zinc-chloride ( Schulze's solution) : — epidermal cells 
turn yellow ; hypodermal sterome, deep purplish brown. 
Chromic acid , concentrated : — epidermis slowly dissolved 
leaving a distinct cuticle behind ; hypodermal sterome slowly 
dissolved. A delicate membrane, the cuticle, was left long 
after all the rest of the section had been completely dissolved. 
The isolated cuticle partly showed the form of the epidermal 
cells, sending off delicate processes of cutin radially between 
the cells. 
Caustic potash : — turns epidermal cells a dark yellowish 
brown, the cuticle is more clearly visible, swelled slightly 
by warming. After boiling for 1*50 min. the cuticle was 
destroyed, also the middle lamella between the epidermal 
cells and those between epidermal cells and peripheral layers 
of sterome. Boiling in potash destroys the reddish brown 
colouring matter of the sterome. 
Aniline chloride : — the reddish brown sterome becomes 
immediately bright yellow ; if the preparation is now washed 
in water, and then treated with cold caustic potash, the brown 
colour of the cell-walls returns. 
Hydrochloric acid : — does not affect the colouring matter 
of the cell-walls of the sterome. 
Nitric acid and chlorate of potash : — cuticle becomes dis- 
