266 KARL lî. KRISTOFFERSON 



got Fi-plants with this character; nor did I notice this character in 

 the Fo-generations of these crosses. 



The genetical behaviour of the character spot indicates that it is 

 due to only one Mendehan factor, 5. 



The colour of the spot is very modifiable to the season, just as 

 was the case with the flower-colour. In spring and autumn it is 

 dark and very easy to see; in the height of summer it is often invisible. 



CHLOROPHYLL- VARIATIONS. 



The pure lines of Viola had a rather different colour as regards 

 the chlorophyll. Line 2, for example, was rather light green; line 10 was 

 considerably darker. The Fi-generation resembled line 10 in this cha- 

 racter. F2 showed a continual variation between the limits of the parent- 

 lines, and was also a little transgressive. Plants were noted that 

 were darker than line 10 and lighter than line 2. However, 

 no attempts were made to classify the material in groups of different 

 shades of colour. Such a classification becomes rather uncertain and 

 is rather troublesome to do. The variation is certainly due to several 

 genetical factors. 



I have also investigated the genetics of another type of chloro- 

 phyll-variation in Viola, viz. a white spotting of the leaves. 



The genetics of the white spotting of leaves show two distinct 

 types — I leave out of consideration the non-hereditary infectious 

 chlorose in Malva (Baur 1906) and other species, and also the albo- 

 variegata and albo-marginata forms. 



In the first type it is very probable that the disposition to the 

 albomaculata-character is localized to other parts of the germ cells 

 than the nucleus. In Mirabilis (Correns 1909) and several other 

 species the descendants of a selfed albomaculata become normal green, 

 albomaculata and white in various ratios. When crossed with a nor- 

 mal green type as male parent the Fi- and Fo-generations show the 

 same behaviour as the female parent, when selfed. If the normal 

 green is used as female parent in the crossings the descendants in Fi 

 and later generations become all normal green. Winge (1919) has 

 investigated the genetics of an albomaculata in Hiimiilus Japonicus. 

 This form breeds true. When crossed with normal green as male parent 

 n\\ descendants in Fi and F. became albomaculata; was the normal 

 green used as female parent they became green. In Capsicum (Ikeno 

 1917 a and b) the Fi-generation becomes albomaculata whether the 



