Wheat tender Different Conditions of Growth . 535 
weekly, the large ones fortnightly, but later the period was lengthened, as 
the supply of plants threatened to run short before maturity was reached. 
For convenience of working, wheat and barley were dealt with in alternate 
weeks. 
As soon as the seedlings appeared above ground in the small pots, 
which was about ten days after sowing, .two unmanured pots and two super- 
phosphate pots were very carefully emptied. The plants were extricated 
without damaging the roots, and the latter were then washed in water with 
a camel’s-hair brush. Sketches of the plants were made and full notes taken 
on the condition of root development. The following weeks this proceeding 
was repeated until all the small pots were emptied. These early plants 
were not weighed, as it was not at first realized what a large amount of root 
growth would be obtained under the given experimental conditions. By 
the time the small pots were finished the top-dressings had been applied 
to the large pots, and henceforward two pots from each manurial series were 
dealt with at a time, making ten plants in all each week. It was of course 
impossible to empty out these large pots without damaging the roots, and 
therefore a jet of water was used to wash away the soil without injury to 
the delicate roots. In the method adopted the pots were placed in 
a horizontal position on a stand of convenient height, with the mouth 
projecting over a large bath, and the soil was washed out of the pot by 
means of a small but fairly strong jet of water. Most of the soil was caught 
by the bath, thus preventing the troubles of drain stoppage, and if by 
chance a portion of the roots became detached it was more easily reclaimed 
than it would have been if the washing out were done directly over a drain. 
In using the jet of water great care had to be exercised to avoid dislodging 
the soil in the middle of the pot first, for if this happened the superimposed 
soil collapsed suddenly and in so doing tore away several of the roots. 
After removal from the pots the roots were carefully freed from adhering 
particles of soil with a camel’s-hair brush, and were then disentangled and 
measured under water to prevent any shrinkage due to drying up. The 
length of the shoot and the number of tillers were noted and after drying 
the roots and shoots were weighed separately. 
A well-developed root system of barley examined half-way through 
growth showed two distinct types of root : (a) long, much-branched roots, 
forming the bulk of the system, and (b) short, white, unbranched roots. 
(a) Branched roots. Seven weeks after sowing the length and number 
of the branched roots varied considerably with the type of manuring, the 
highest number occurring with the superphosphate, and the lowest with 
the unmanured plants. In the more heavily manured plants laterals were well 
developed and tended to become concentrated in the upper 10—12 in. of the 
roots, while in the unmanured and the nitrate only plants the laterals were 
not so well developed and were much more scattered. As growth proceeded, 
