490 WHITE— STUDIES OF INHERITANCE IN PISUM. 



view point is a joint expression of factors or of a group of factors 

 and a particular environment. Characters are not inherited, since 

 they cease to exist when unexpressed. Latency, semi-latency, and 

 patency of characters are terms that should be scrupulously avoided 

 in the interests of clear thinking. The older school of biologists and 

 systematists in particular have always regarded all character ex- 

 pressions of a particular kind, such as the white color of flowers in 

 different plant species, the character of stems — whether fasciated 

 or round, the number of floral parts, etc., wherever found, as iden- 

 tical. For example, fasciation, according to de Vries, is a very 

 ancient character, which has been transmitted to many of the higher 

 forms of plant life in a latent condition. In a publication now in 

 press in Germany (98.5) the writer believes he has set forth suffi- 

 cient evidence to show that fasciations in plants from a genetic 

 standpoint are of many kinds, some of which are hereditary under 

 almost any normal plant environment, while other types only appear 

 as a response to special environments, such as very rich soil, over- 

 watering, or the stimuli derived from insect depredations. Further, 

 these two or more kinds of genetically distinct fasciations, though 

 morphologically indistinguishable, may be present at the same time 

 in a group of plants such as peas. Further discussion of this case 

 will be given in the part devoted to the genetics of Pisum stem char- 

 acters. Morgan and his students (61) evidently look upon a char- 

 acter in this same fashion. They regard the recessive and dominant 

 white color characters of certain breeds of silkworms and poultry 

 as two different kinds of white due to two different genetic factors. 

 White in both races is indistinguishable except in breeding tests. 

 They cite numerous other cases among which is one from Baur 

 illustrating the part environment instead of hybridization may play 

 in showing up this difference. The red primrose {Primula sinensis 

 rubra) reared in shade and moisture at a temperature of 30°-35° C. 

 has pure white flowers, while the same plants grown at i5°-20° C. 

 have red flowers. White and red flowers will occur on the same 

 plant if the plants are first allowed to bloom in the cooler tempera- 

 ture and later to continue their blooming under the higher tempera- 

 ture. Another race of primrose {Primula sinensis alba) always has 

 white flowers, even at 20° C. The white flower color character of 



