DOMESTICATED PLANTS — BLAYDES 331 



many of the leaves seen in the ilhistration. Each varigated leaf then 

 is made up of two genetically different tissues instead of one, as is 

 usual. When variegated leaves of this African violet are used as 

 propagules, the young plants are usually green, as typical of the orig- 

 inal parent, or they are so chlorophyll-deficient that adequate sugar 

 is not made and they soon die of starvation. The variegated state can 

 be propagated from stem cuttings, but this is difficult and not practical 

 since the internodes of the stem are very short and ordinarily there 

 is only one terminal vegetative bud. The lateral or axillary buds 

 ordinarily are inflorescence buds and their growth is determinate. 

 Similar mutants have been observed in plants derived from leaf cut- 

 tings in varieties sold under the names "Mentor Boy," "Red Head 

 Girl," and "'\^Tiite Lady." The same kind of mutation has probably 

 occurred in many varieties oiSaintpauUa. 



In most variegated plants, the stem internodes are much longer than 

 in Saintpmdia, and the axillary buds are more likely to be vegetative 

 rather than reproductive. Examples of this will be recognized in the 

 common varieties of geranium {Pelargoniuin) and Goleus. In such 

 examples numerous stem cuttings may be made from a single plant. 

 If these stem cuttings are chimaeras, then the chimaeral or variegated 

 condition may be propagated. Mutant tissues in a chimaera may be 

 distributed in a plant organ in one of three ways: (1) periclinal, (2) 

 sectorial, and (3) mericlinal. The periclinal chimaeras are the most 

 stable of the three types. This one is characterized by the mutant 

 tissue forming a solid sheath about the whole organ. The red skin of 

 a Red Triumph potato tuber (pi. 10, fig. 38, J., 5) is an example. The 

 sectorial type (pi. 10, fig. 39 ; pi. 11, fig. 40) is the least stable as far as 

 the chimaeral condition is concerned. The mericlinal type is char- 

 acterized by an uneven distribution of the mutant tissue in the organ, 

 forming streaks, splotches, or mosaic patterns. The mericlinal type 

 is less stable than the periclinal, but more permanent than the sectorial 

 form. Most variegated ornamental plants fall in this class. 



The variegated geranium {Pelargonium) listed as "Silver Leaf 

 S. A. Nutt" (pi. 7, fig. 29) is a fairly stable chimaera exhibiting albino 

 tissue about the border of the leaf blade. When branched plants are 

 cut back and lateral buds are forced to develop, occasionally a stem is 

 found which bears green leaves with no variegation (fig. 29). Less 

 frequently an albino branch may develop laterally from a larger stem 

 which bore typically variegated leaves. Cuttings from the green 

 branch will multiply vegetatively and continue to be entirely gi-een. 

 Cuttings from the albino branch will not survive because of the lack 

 of sugar. 



Another variegated geranium {Pelargonium) , variety "Mme. Sol- 

 leroi," has a chlorophyll-deficient (yellow-green) area radiating from 



