PLANT BREEDING I 43 5 



(2) The number of chromosomes in the h^'brid A. lafi folium X A. 

 inajiis is also iS. 



(3) The shape of the chromosomes is the same in all the plants stu- 

 died. 



The results of the investigations on the size of the nucleus are as fol- 

 lows : 



Number 



of nuclei Average 



measured diameter 



.4. latiiolium ; . . 120 7.01 [J. = 100 



A. majxis 75 6.84 [X ■- 97 



A. tortuosum 45 6.01 [^ = ^5 



A. majus X ^- lortiiosum 96 6.04 [JL = 86 



These results show that : 



a) The size of the nucleus in the pollen mother-cells at the phase 

 of synapsis is almost the same in A. latifolhim and A. ma jus, .while the 

 nucleus of A . tortuosum is considerabh' smaller. 



b) The difference between the size of the nuclei in A. tortuosum 

 and in A. majtis and A. latifolium finds a parallel in the external morpho- 

 logical character of these types. 



c) The nuclei of the hybrid A. majits x A. tortuosum are the same 

 size as those of A. tortuosum. 



The differences in the size of the nuclei in these varieties of Antir- 

 rhinvun lead one to suspect other morphological dift'erences may exist 

 between the nuclei, though they escape detection for the time. It might 

 repay investigation to examine various other plants in which the shape 

 and number of the chromosomes are the same, but in which the dimen- 

 sions of the nuclei differ. 



The article is followed b}^ a resume (pp. 294-309) of present-day theories 

 of the nucleus as transmitter of hereditary characters. A bibliography 



of 95 publications is appended. 



• 



1071 - A Case of Variations Observed in the Potato in Holland. — v.\x luijk in Cuiiura 



28th year, No 332, pp. 124-127. Wageningcn, i')i6. 

 A mother plant of the variety I^eeuwsche blauwen known by the num- 

 ber 07 was isolated in 191 t for the purpose of investigations on " mosaic 

 disease ". Among its direct descendants a perfectly healthy individual 

 suddenly appeared in 1912, which was distinguished from the rest of the 

 plants by the greater rigidity of its stem, its heavier weight (2.9 lbs. 

 heavier), by the colour of its tubers, (deep violet instead of violet), and by 

 the elongated oval shape of its tubers. This is an interesting case of varia- 

 tion. 



The tubers from the varying individual were planted in pots, and 

 in 1913, 95 plants were obtained which naturally grouped themselves into 

 four divisions : 



i) 76 plants susceptible to mosaic disease. vSonie of these resem 



