442 
CECIL YAMPOLSKY 
de Vries, H. 1903. Die Mutationstheorie 2: 638, fig. 144. 
Weiss, F. E. 1906. Die Bliitenbiologie von Mercurialis. Ber. Deutsch. Bot. Ges. 24: 
501-505. 
Wilson, M. 191 5. Sex determination in Mnium hornum. Annals of Botany 29: 433. 
Wuist, E. D. 1913. Sex and development of the gametophyte of Onoclea Struthioptens . 
Physiol. Researches i: 93-132. » 
Yampolsky, C. 1916. Observations on inheritance of sex ratios in Mercurialis annua. 
Mem. N. Y. Bot. Gard. 6: 69-74. 
EXPLANATION OF PLATES XXXVII— XL 
Plate XXXVII 
Fig. I. Male plant of Mercurialis annua 3 weeks old. 
Fig. 2. Female plant of M. annua 3 weeks old. 
Fig. 3. Male plant of M. annua 6 weeks old. 
Fig. 4. Female plant of M. annua 6 weeks old. 
Fig. 5. Branch of monoecious individual showing the frequency of distribution of 
male and female flowers: male flowers at a, female flowers at h. The anther sacs have 
discharged their pollen. 
Fig. 6. Branch of female individual showing the presence of one male flower and 
many female flowers: a, male flower; h, female flower. 
Fig. 7. Branch of female individual showing the presence of two male flowers, female 
flowers, and maturing seed: a, male flower; h, female flower; c, maturing seed. 
Plate XXXVIII 
Female plants 3 months old; seed set by pollination from male. 
Plate XXXIX 
Male plants 3 months old, grown from same series of seed as female. 
Plate XL 
Fig. i. Branch of male plant no. 279, showing appearance of seed on male branches. 
Fig. 2. Branch of male plant no. 280, showing appearance of seed on male branches. 
