Growth o/"Lemna minor in Mineral Culture Solutions. 497 



Table IX. 





T)i*b fifi 



Dish 67 



Dish 68 





Tiiah 70 



IVXean 



Number of plants — - 















7th week (at begin- 







34 



oy 



oo 



Afi -ft 



ning) 















8th week 



138 





i nc 



180 



90 



143 - 6 



9th „ 



524 



680 



444 



648 



480 



555 - 2 





1,056 



1,344 



9/b 



1,360 



840 



1,115 '2 





2,944 



3,232 



2,208 



3,792 



2,128 



2,860 "8 



12th „ 



6,272 



7,360 



4,320 



5,920 



4,160 



5,606 -4 



13th 



16,576 



19,008 



12,800 



22,656 



10,944 



16,396 -8 



Weight of plants — 



mgrm. 



mgrm. 



mgrm. 



mgrm. 



mgrm. 



mgrm. 



8th week 



16 -0 



19-6 



9 6 



16 -0 



11 -2 



14 -5 



9th „ 



56 -0 



66 -4 



52 -0 



67 -2 



45-6 



57-4 



10th „ 



123 2 



142 -4 



116 8 



148 -8 



83 "2 



112 -9 



11th „ 



355 2 



412 -8 



300 -8 



489-6 



272 -0 



366 -1 



12th „ 



1 ,004 -8 



1,126 -4 



736 -0 



953 -6 



652 -8 



894-7 



13th „ 



2,624 -0 



2,764 -8 



2,086 -4 



3,648 -0 



1,817 -6 



2,588 -2 



Series VI to start the new series. The numbers given in the Table for 

 Series VI, however, represent not the halves which were left and which 

 would correspond with the new series, but the complete sets which would 

 have been obtained had the contents of the dishes not been halved. It is 

 evident, therefore, that the numbers for Series VII from the 3rd week 

 onwards correspond to one-half of the numbers given for Series VI for the 

 same period, and that, in order to obtain a correct comparison, one-half of the 

 mean numbers for Series VI must be put at 100, and the corresponding 

 numbers for Series VII then calculated. Similarly, Series VIII was started 

 at the 7th week of Series VI, at the fifth time of halving these dishes. 

 One thirty-second part of the complete sets for Series VI was therefore used 

 to start Series VIII, and the numbers for the latter series from the 7th week 

 onwards correspond to 1/32 of the numbers given for Series VI. In order 

 therefore to correctly compare the rate of growth in these two series, the 

 mean numbers for Series VI must be divided by 32, and the resulting figures 

 put at 100, to obtain the corresponding numbers for Series VIII. A com- 

 parison thus obtained for both numbers and weights is given in Table X 

 on p. 498. 



The average weekly weight of 100 plants in each of the three series is 

 shown in Table XI on p. 498. 



The drop in the average weight of the plants in Series VII from the 7th to 

 the 9th week is probably explained by the excessive multiplication of the 

 plants during a fortnight of extremely hot weather An abnormally large 

 number of small new plants were thus included in the weekly countings, and 

 this resulted in a smaller average weight. 



VOL. LXXX1X. — B. 2 U 



