214 SCIENCE PROGRESS 



character. The crowns formed later by these seedlings, how- 

 ever, exhibit a somatic segregation which may result in the 

 reappearance of the regular type of variegation. Moreover, all 

 four types — viz. green, white margin, white middle, irregularly 

 striped — may be exhibited by the different crowns produced 

 from a single variegated seedling. 



Several leaf-colour types have been recognised in the maize. 

 In addition to normal green and pure albino there is a type in 

 which the seedlings are at first albino, and become green as 

 they develop, another variety in which the colour is a uniform 

 yellowish-green, and the striped variety. These have been 

 studied from the cytological standpoint by Randolph {Bot. 

 Ga^., vol. Ixviii, pp. 337-75). It appears that the protoplastids 

 from which the chloroplasts arise are all of one type, and the 

 green and colourless plastids respectively are to be regarded as 

 the extremes of a series in which all intermediate conditions 

 are presented. The apparently sharp line of demarcation 

 between the yellow and green regions of the striped variety 

 presents in reality plastids of varying sizes and depths of colour 

 even within the same cell. 



The variability of leaf form in Taraxacum is a familiar 

 feature to all field botanists, and Sears, who {Bot. Gaz., vol. xxiii, 

 pp. 425-41) has grown numerous plants under varying condi- 

 tions, finds that dissection of the leaves increases with the age 

 of the plant, and often the degree of hairiness also. This change 

 is exhibited in both moist and dry conditions, but multicipital 

 branching brings about rejuvenescence with a recurrence of the 

 sequence. 



Tammes {Jour. Genetics, vol. xii, pp. 19-46) has studied the 

 genetical composition of Linuni iisitatissimutn with respect to 

 colour. Six factors determine the colour of the flowers, and of 

 these two, which must both be present, are essential whilst the 

 rest are intensification factors. Two of these, with an addi- 

 tional factor, determine the blue colour of the anthers, whilst 

 still another determines the brown colour of the seed coat. 

 The eight factors thus concerned with colour are all present in 

 the common blue Flax, and all the other types studied were 

 found to be of the nature of loss mutants. 



A remarkable Narcissus growing wild and perhaps a mutant 

 of N. angustifolius has been found in the Vaudese Alps by 

 D. Rieser {Bull. Soc. Vaud. Soc. Nat., 53, pp. 341-2). The outer 

 three perianth segments are broad and trilobed, whilst the three 

 inner are laciniate at the base with a long and narrow median 

 segment. Of the six stamens the three inserted at the mouth 

 of the yellow corona are sterile. 



Ecology. — Working with a fertile calcareous soil rich in 

 plant food and having a maximum' water capacity of 45 per 



