192 lojinence of Seed Weight, etc. on tin Potnto Crojt 



Turning to tlie production of the lighter tubers in the yields, two 

 facts emerge. In the series A-D, the quantity of "chats" decreases in 

 direct ratio with the weight of the set, and therefore in the same ratio 

 as that of the " ware" in the same yield. On the other hand, in the E and 

 F tuber-set series the amount of " chats " is much in excess of that found 

 in any of the A-D groups. So that it would appear from these results to 

 be very clearly demonstrated that heavy sets, weighing 1 ozs. and over, 

 not only give greatly reduced ([uantities of useful heavy ware, hut also 

 return in tlieir produce an altogether exce-^sive proportion of useless 

 chats in comparison with the yields rendered by tuber-sets of smaller 

 size. This result is entirely in accord with that obtained in the favourable 

 season of 1920, when the sets weighing 4 ozs. and over produced roughly 

 twice as many chats, and one-third or more less ware, than the sets of 

 lighter weight. 



A similar analysis of the yields was made of the tuber-sets groups 

 H, I, .1 and K, and the results are shown in Fig. 4, where they are placed 

 in comparison with all the other groups represented in the same portion 

 of the experimental plot. In this series the outstanding fact is the 

 enormous proportion, viz. 4U per cent., of heavy ware produced by the 

 K series. If reference be made to Kig. 1 it will be seen that series K 

 and F were grown in the same line in the same portion of the experi- 

 mental plot, and so may be fairly compared. The F series, however, are 

 tuber-sets of 5-:53 ozs., whilst the K are outgrowths of 1-25 ozs. in weight, 

 and the great disproportion, between 5 per cent, and 40 per cent, of the 

 whole sample, the quantities of heavy ware produced by them res{)ec- 

 tively, is confirmatory evidence of the previous deduction, that the 

 Ughter the weight of the tuber-set, the greater the proportion of heavy 

 ware produced. 



This relation of size of set to quantity of heavy ware was observed 

 by Sir Thomas Middleton^, but liis results were unknown to the author 

 till after this paper was written. 



No explanation is advanced either of this relation or of that between 

 the weight of set and the weight of the total crop, but it is permissible 

 to suggest that both phenomena may be related to the le.sser maturity of 

 small tubers. 



In each of the analyses of crops made, — and many were duplicated — 

 record was kept of the presence of secondary outgrowths on the tubers. 

 Doubtless owing to the fact that this particular i)iece of land never 



' Midilleton, T. H., "Potato Ex]K'rinu'ntH at l{iiii;o\ lie's Farm, Impingtoii, Ciiinbs.," 

 The Pdldlo Year liuok, 1907. 



