602 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



4. Old garden soil from the Chelsea Physic Garden ; bad plants 

 occurred in this soil in 191 1. 



Eight tubers, chosen from the specially selected ones scheduled 

 in Table I., were potted in each of the four soils used, as follows : 



Table Numbers 



Potted in Wisley soil 17 3 2 20 13 22 1 19 



„ Dunbar ,, 15 24 8 26 14 21 5 16 



M Wye „ 65 57 67 68 53 64 61 56 



,, Chelsea ,, 12 6 9 10 7 4 18 11 



The pots were then kept in the greenhouse attached to the 

 Laboratory. 



The plants very soon showed pathological symptoms precisely 

 similar to those so familiar in the field crop. Yellowness was first 

 observed in sprouts in Dunbar soil towards the end of February. 

 These recovered and by the end of March all the plants in Dunbar 

 soil were green, but the leaves on two plants grown in Chelsea soil 

 were yellow and curled. On May 2, plants from tubers 65 and 67, 

 in Wye soil, 20 in Wisley soil, 26 in Dunbar soil, and 11 in Chelsea 

 soil, showed typical bad foliage. Thus bad plants, similar to those 

 occurring outdoors later in the year, were produced in all the soils 

 selected. 



E. — Effect of Planting Tubers produced by Bad Plants. 



The tubers used were obtained from the following sources, and 

 their characters are tabulated in Table IV. 



(a) Sent by Professor E. S. Salmon from the South-Eastern 

 Agricultural College, Wye, the produce from bad plants marked at 

 Wye by the writer in 1911 (tubers 1-14). 



{b) Sent by a grower from bad plants growing near Edinburgh 

 (tubers 15-20). 



(c) Sent by a grower from bad plants at Dunbar in 191 1 (tubers 

 (21-26). 



The tubers received from Wye had been removed from bad plants 

 by Professor Salmon, and the produce from each bad plant enclosed 

 in a separate parcel. The contents of each parcel were photographed 

 upon arrival at Wisley, so that each group in figure 193 — marked 

 Plant 1, Plant 2, and Plant 3 respectively — represents the total 

 produce from a bad plant. 



Three lots were selected for the experiment, lot 1 consisted of 

 tubers 1-3, being the produce of a single plant grown at Wye (see 

 fig- J 93) '> l°t 2, of tubers 15-17 from near Edinburgh; and lot 3, of 

 tubers 21-26 from Dunbar. 



It will be seen both from the table and the photographs that the 

 tubers produced by bad plants are of small size — the largest recorded 

 in the table weighing only 52 grammes. This is the common experi- 

 ence with the 1 President.' 



