258 ~ Stnrtevant. 



cussed. I refer to the behavior of the plastids in plants. These bodies 

 seem to show the same kind of genetic continuity as do the chromosomes, 

 and are therefore supposed to be efficient bearers of hereditary qualities 

 from one generation to the next. The evidence in favor of this inter- 

 pretation was very forcibly presented by de Veies ('89), and then was 

 immediately dismissed by Mm on the basis of his observation that the 

 plastid color of hybrids between races differing in this character is 

 usually influenced by the male parent as much as by the female, although 

 the plastids themselves are probably all of maternal origin. There the 

 case would probably stand now, were it not for the experiments of 

 CORRENS ('09) on Mirabilis jalapa. In this plant there occurs a form 

 which is spotted with white and green (plastid colors). All flowers on 

 green branches give purely green descendants, while flowers on wliite 

 branches give white seedlings; and flowers which come in such regions 

 that they are partly wliite, partly green, usually give green offspring, 

 white ones, and some spotted ones again. The whites die from lack 

 of chlorophyll, and the spotted plants behave as did their mother. The 

 pollen never bears the white gene but is always pure for green; and 

 the behavior of the ovules of a given flower is not influenced in any 

 way, as regards this character, by the pollen which fertilizes it. Here 

 then we have a character transmitted only through the egg, capable of 

 being perpetuated thus indefinitely, in no way influenced by the male 

 parent, and showing somatic segregation. Correns compares the case 

 to that of the transmission of a disease by infection from mother to 

 child, and to the effects of the vigor of parents upon that of offspring. 

 He is inclined to rule the case out of court, and to say that it is not 

 inheritance at all. This seems to me to be hardly justifiable, for we 

 can refuse to call this inheritance only by making a very narrow definition 

 of the term. This case and the somewhat similar one in Pelargonium 

 reported by Baue ('10) seem to me to show that we must be prepared 

 to admit that the nucleus is not the sole cell organ involved in heredity'). 

 The chondriosomes, for example, may be responsible for the transmission 

 of certain characters, as maintained by Meves and others. However, it 

 seems to me that we need more evidence, especially on the experimental 

 side, before we can speculate to much advantage about these bodies. 

 Cases of inheritance which demand a body other than the chromosomes 



^) It is possible to explain the Mimhilis case on a chromosome basis by a method 

 similar to the one suggested below for Oenothera and Matthiola, but this explanation 

 does not seem to me to be very plausible. 



