yampolsky: inheritance of sex-ratios in mercurialis 71 



Mercurialis annua, an annual weed, is described as occurring 

 in three forms — female, male, and hermaphrodite. Some female 

 plants, it has been established, produce a few male flowers and 

 are self-fertile. Some male plants occasionally produce a few 

 female flowers and they are self-fertile. The pollen from a male 

 plant upon a female produces seeds readily and in abundance. 

 The interesting observations recorded show that the seeds from 

 the selfed females produce exclusively or almost exclusively 

 female offspring; the seeds from selfed male plants produce ex- 

 clusively male plants (Strasburger) ; the seeds from the cross 

 pollinated plants produce approximately a fifty to fifty ratio of 

 males and females. Mercurialis then records the so-called 

 gametic constitution of its sexual cells directly in self fertilization. 

 The male cannot be regarded as heterozygous for sex in Correns's 

 words since the offspring produced from its selfed seed are only 

 males, nor can the female be heterozygous for sex as Bateson 

 assumes since the offspring produced from selfed seed are only 

 females. Strasburger assumes that in the case of the approxi- 

 mately half and half production of males and females in the cross- 

 pollinated plants of Mercurialis annua it is the male plant that 

 determines the result. He interprets the phenomena of seed from 

 selfed female plants which give rise to females and seeds from 

 selfed male plants that give rise to male plants as evidence of 

 the well-known breeding fact that "like tends to beget like." 



The present work was begun in February, 19 14, and this com- 

 munication deals primarily with female cultures of Mercurialis 

 annua. A single vigorously growing female plant had produced 

 in January, 1914, 42 seeds. By April, 1914, the plant had pro- 

 duced 24 more seeds. The first lot of seeds was sown, 36 germi- 

 nated, and 36 plants were raised to maturity, all of which were 

 females. The second lot of seeds gave 14 plants, all of which 

 were females. Records of all these plants have been kept and 

 at the present time offspring up to the fifth generation have 

 been secured. I have made the following grouping of the plants 

 under my observation: 



No. seeds 



produced No. plants 



I. Mother plant 66 50 Fi 



II. Fi plants 979 197 F2 



III. F2 " 79-h? 53 F3 



IV. F., " 367 118 F4 



V. F4 " Not counted Fs 



