182 
JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
In both plants the heights were too unequal to allow of a fair 
average being arrived at. The radicles that penetrated the clay 
and reached the sides of the pot were very luxuriant and 
produced an abundance of root-hairs. Those that were in the 
middle of the clay, and which were, by reason of their position, 
debarred from reaching the sides of the pot so speedily, were 
stunted in growth and had but few hairs. 
(2.) Pebbles.— Mustard, average height 15—16, length of 
tigellum 4—6, length of radicle 8—10 centimetres. Cress, 
8—9, 2, 6—7 centimetres. 
In this case some of the sand that had been scattered over 
the surface was washed down between the pebbles. The root 
fibrils of the Mustard were directed obliquely downwards, and 
had but few root-hairs. The Cress also had few hairs. 
(3.) Ballast. —Mustard, 15, 5—6, 10—12 centimetres. 
Cress, 7—9, 3—4, 5—6 centimetres. 
The radicles of the Mustard were straight, unbranched and 
with few root-hairs; those of the Cress were directed more 
obliquely, were somewhat more branched, and had very few hairs 
except where they came into contact with the sides of the pot. 
(4.) G-arden Soil. —Mustard, 12—13, 6, 6—7 centimetres. 
Cress, 13—14, 4, 9—10 centimetres. 
The radicles of the Mustard were slightly branched, the fibrils 
spreading horizontally, but with few root-hairs. The radicles 
of the Cress were perfectly straight and unbranched, with few 
root-hairs except near the sides of the pot. 
(5.) Flannel.— Mustard, 4—5, 3—4, 1—2 centimetres. 
Cress, 3—4, 2—3, 1—2 centimetres. 
In the centre of the pot where the flannel had become dry, 
the radicles shrivelled and died from below upwards. Near the 
sides of the pots, however, the vigour of the seedlings was greater 
and the number of root-hairs larger. 
(6.) Decayed Leaves. —Mustard, 12, 8—9, 3—4 centimetres. 
Cress, 8, 4—5, 3—4 centimetres. 
In this pot the great proportionate length of the tigella or 
caulicles was remarkable. The downward growth of the radicle 
was impeded by the layers of tough leaves. At the sides of the 
pots the radicles and root-hairs were most abundant, and on the 
surface of the leaves themselves the hairs were relatively very 
numerous. 
