The Inheritance of Acquired Characters 33 



As an example of the sort of thing that in:iy occur among 

 fungi, the work of Long (14) may be mentioned. Piicciuia Eliis- 

 iana and P. Andropogonis both grow, in one stage, on Aiidro- 

 pogon, where they are to be distinguished by morphological differ- 

 ences in the uredospores. P. Ellisiana has Viola for its alternate 

 host, while P. Andropogonis has Pcntcstemon. P. Ellisiana, how- 

 ever, has been artificially induced to infect Petitestcmon , where it 

 produces spring spores that resemble those of P. Andropogonis. 

 When these spring spores are returned to Andropogon, the result- 

 ing uredospores are morphologically identical with P. Andropo- 

 gonis uredospores. Conversely, P. Andropogonis can be made to 

 infect Viola, where it produces morphologically P. Ellisiana spring 

 spores, and these will bring P. Ellisiana uredospores when returned 

 to Andropogon. 



This appears to be an actual change in species through a 

 change in the quahty of the nutrition. But can it be demon- 

 strated that the two forms were really distinct "species" in the 

 first place? 



The findings made by Williams (19) on periodicity 

 of sex cells in the marine alga, Dictyota dichotoma, rather 

 clearly indicate inheritance of acquired characters. In 

 any one locality the male and female organs originate 

 simultaneously and pass through their successive stages 

 of development together; a general liberation of gametes 

 and fertilization takes place on a particular day. This 

 period differs between different localities and varies 

 slightly at any one locality, at all times showing a clear 

 relationship to the tides, and therefore to the amount of 

 light that reaches these submerged plants. So intimate 

 is the foregoing relationship that one can })re(lict the time 

 of liberation and fertilization by consulting the almanac 

 of the locality. On the other hand, there is no evidence 

 of periodicity in seas where there are no tides. Plants 

 transferred to aquaria in the laboratory, and thus 



