No. 511] NOTES AND LITERATURE 



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existe between a small green fleck on a leaf and a typical green 

 branch. 



The variegated types do not reproduce strictly true to seed. 

 They sometimes throw green plants. These green plants do not 

 simply represent extremes of variation because they are too 

 numerous and offer a secondary maximum in the curve of dis- 

 tribution. On the other hand, variegated plants have thus far 

 not produced any of the pure chlorina type. Some of the pure 

 green reversions produced progeny all of which are green. A 

 larger number gave some variegated and some green, the green 

 nearly always predominating in the progeny. The thus obtained 

 variegated plants gave some normal green progeny, and the nor- 

 mal greens thus obtained gave only occasionally all normal greens. 

 A green branch on a variegated plant, when self fertilized, gave 

 three variegated and four green plants. It was not possible to 

 explain variegation in these species as a cross between the chlo- 

 rina and the normal green types. In the cross between chlorina 

 and typica (normal greens) the latter is dominant, but not abso- 

 lutely so. The chlorophyll content of the hybrids is about 90 

 per cent, of that in the normal greens. In some cases in the 

 second generation of this cross, the hybrids split into chlorinas 

 and greens in perfect Mendelian fashion. In others variegated 

 plants occur in the second generation ; the reason for this is 



Dwarf and normal stature behave as a pair of Mendelian char- 



