EXPERIMENTS IN CULTIVATION OF POTATOS. 125 
size cut in half lengthwise at planting time to make forty plants gave 
95 lb. 10 oz. ; twenty of the same size cut in half lengthwise in January, 
of which thirty-eight halves survived, gave 71 lb. ; twenty of the same 
size cut in half transversely to make forty plants gave 84 lb. 10 oz. 
II. The Effect of Various Coverings on Cut Surfaces 
of Potato Tubers. 
In order to test the effect of various substances which might be used 
for covering the surface of tubers cut for propagation purposes in 
order to prevent loss of moisture, &c, a number of tubers of seed 
size (var. ' Factor ') were cut lengthwise in January and dusted with 
the substances mentioned in the following table. The cut tubers 
were planted in mid-April after sprouting, in rows 27 inches apart and 
18 inches apart in the rows, and the different groups of twenty cut 
pieces arranged as in Series I. 
Covering. 
No. of plaDts sur- 
viving out of 20. 
Weight of Crop. 
lb. oz. 
r . 
No covering .... 
20 
28 10 
2. 
Keen's Cement . . 
19 
33 15 
3- 
Painter's Knotting . . • . 
16 
21 6 
4- 
Size ..... 
20 
32 13 
5- 
Loam 
19 
24 IT 
6. 
Sand ..... 
16 
26 8 
7- 
Plaster of Paris 
19 
38 8 
8. 
Flowers of Sulphur . 
20 
32 4 
It seems evident that plaster of Paris is one of the best materials 
for checking loss of moisture where tubers are cut before planting, 
while Keen's Cement, Size, and Flowers of Sulphur follow. As might 
be expected, loam and sand are of little use, but Painter's Knotting, 
strangely enough, seems actually detrimental, for, while four of the 
twenty halves died, the surviving sixteen gave a smaller average crop 
than any of the others. 
III. Effect of Greening and Number of Sprouts on Seed 
Potatos on Yield. 
The importance of sprouting potatos before planting them is now 
almost universally recognized, although there still prevails an erroneous 
idea that sprouting is necessary only in the case of early varieties. The 
increase in yield of all varieties through sprouting has been found to 
average two tons to the acre, and it is therefore manifest that sprouting 
before planting ought not on any account to be neglected. In this 
experiment the results of sprouting in full light show only a negligible 
advantage over those obtained by sprouting in the dark ; but it is 
to be observed that the short, sturdy sprouts formed on tubers 
