126 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
sprouted in the light are less liable to damage during planting than are 
the more slender, delicate shoots produced when tubers are sprouted 
in the dark. 
At the same time the yield oi tubers sprouted in trays, whether in 
the light or in darkness, is in remarkable contrast with that of tubers 
of the same stock kept in the clamp and urged to the pioduction of 
spindly sprouts exhausting the tuber by the conditions there. 
Group. 
Treatment. 
No. of 
sprouts left 
when 
p.anting. 
Yield. 
Ware and 
Seed. 
Chats. 
Total. 
ib. oz. 
.t>. oz 
ib. oz. 
1 
Greened and sprouted 
I 
4i 13 
O L 2 
42 9 
2 
>i >> 
2 
49 2 
O 14 
50 O 
3 
>> >> 
none 
31 6 
1 M 
33 4 
4 
>> >> 
ail 
48 9 
I I4 
50 7 
5 
Sprouted in dark 
i 
44 1 
O II 
44 12 
5 
j> • »i 
2 
49 4 
I O 
50 4 
7 
>i ») 
none 
37 7 
1 4 
38 11 
8 
>> >> 
all 
4 1 15 
0 11 
42 10 
9 
Kxhausted and shrivelled in clamp 
i 
37 13 
1 1 
^8 14 
lo 
j» >> 
2 
41 6 
1 0 
42 b 
II 
>> >> 
none 
23 3 
2 3 
25 6 
12 
> j ) ? 
all 
34 2 
2 14 
37 0 
The variety used was ' Factor,' as in Series I. and II. ; the tubers 
were of seed size ; and they were planted as described in the first two 
series. Twenty plants were grown in each group. The superiority 
of the seed sprouted in trays over that allowed to sprout and exhaust 
itself in the clamp is plain from the foregoing table, ior the average 
yield of the tray-sprouted seed was 2 lb. 2J oz. of useful produce, 
while that from the clamp-exhausted tubers was only 1 lb. 10 oz., 
an advantage of over J lb. a plant in favour of tray-sprouting. 
It is also evident that in all cases it was better to leave one sprout 
than to rub all off at planting time, and better still to leave two sprouts 
than one. To leave two sprouts seems also better than to leave all 
produced ; the advantage is shown both in total yield and in the 
weight of chats produced, for usually more chats were produced 
where all sprouts were left than where all were removed but one or 
two. 
The reduction in crop where all the sprouts are removed is doubtless 
due in part to partial exhaustion of food material, and in part to delay 
in starting growth and the consequent shorter growing period. The 
latter point is well illustrated in Series VI. of these experiments. 
IV. Effect of Size of Seed on Tuber Yield. 
Another series of experiments throws some light on the reason 
of the low yields from exhausted tubers seen in Series III. The small 
tubers of one ounce gave a markedly smaller yield than those of two 
