No. 504] 



NOTES AND LITER I TUBE 



817 



we desire to ascertain, is commonly fertilized by a sperm-cell 

 of the same species. The sex-tendency of both gametes is un- 

 known. On the other hand, the sex of the offspring resulting 

 from the union of the gametes becomes obvious. In other words 

 by the interaction (in union) of two unknown quantities, X and 

 Y, i. e., the sex-tendencies of the two gametes, there results an 

 organism of known sex; or x-\-y=--sex of organism. Could 

 the value of either x or y be ascertained the equation could be 

 solved and the value of the other unknown quantity determined. 

 These values Correns obtains in the case of the germ-cells of 

 two favorable, nearly related, species of plants one of which is 

 hermaphrodite and the other dioecious. The above figure is not 

 quite accurate, as Correns point out, since a solution of the 

 equation is possible only when the unknown sex-tendency of the 

 germ-cell of dioecious type, as over against the known sex-tend- 

 ency of the hermaphrodite germ-cell, is so strong as to wholly or 

 almost entirely prevent the development of the latter or to 

 greatly suppress it. The conditions are fully met in those cases 

 where the sperm-cell of a white-flowering pea by fertilization 

 makes possible the development of the egg-cell of a red-flowering 

 pea, so that a red-flowering plant results without showing a trace 

 of the white factor of the sperm. Thus is obtained the effect of 

 artificial parthenogenesis, not only on the egg cell but also on 

 the sperm-cell. 



The germ-cells of hermaphrodite forms carry the hermaph- 

 rodite sex-tendency and give rise only to hermaphrodite forms. 

 Correns does not regard a hermaphrodite individual as a 

 "mosaic" derived from the union of a germ-cell of male tend- 

 ency with one of female tendency. However, they must contain 

 the anlagen of such a mosaic. Hermaphrodite germ-cells contain 

 only the hermaphrodite sex-tendency both in the egg-cells and 

 in the sperm-cells. Likewise for monoecious forms, where on the 

 same individual two kinds of sexual flowers appear, male and 

 female, the same position must be taken; i. e., that both kinds 

 of germ-cells, eggs and sperm, carry the same tendency, namely, 

 the tendency to develop into monoecious forms. Each germ-cell 

 thus carries over not the sex of the flower from which it came, 

 but that of the entire plant on which the sexual flowers appeared. 



There remains no doubt concerning the monoecious tendency 

 of the germ-cells of monoecious plants. Correns cites in further 



