RECENT ADVANCES IN SCIENCE 40S 



Ledoux {Bull. Soc. franc. Mm. 39, pp. 232-80, 19 16) discusses 

 from the theoretical point of view the geometrical properties 

 of solid solutions, with reference to the monoclinic and ortho- 

 rhombic pyroxenes. Larsen (Amer. Miner. 2, pp. 17-19, 191 7) 

 points out that massicot consists of two different crystalline 

 forms of lead oxide, and suggests certain modifications in 

 nomenclature in order to prevent confusion. 



BOTANY. By E. J. Salisbury, D.Sc, F.L.S., East London College, 

 University, London. 



General. — The current volume of the Journal of the Royal 

 Horticultural Society contains an interesting paper by E. A. 

 Bunyard on the History and Development of the Red Currant. 

 Three species are regarded as being concerned, viz. Ribes 

 vulgar e, R. rubrum and R. petrceum. The garden Red Currants 

 are probably the outcome of breeding between these wild 

 species. The macrocarpum section, however, appears to have 

 originated in a mutation from R. vulgare. 



Various writers have called attention to occasional speci- 

 mens of Myrica gale on which both male and female flowers 

 were present on the same shoot, and one instance has been 

 recorded in which the flowers were hermaphrodite. Davey and 

 Gibson (New Phytologist, vol. xvi. 191 7) have made a detailed 

 study of the distribution of sex in this species, and find that all 

 gradations between the male and female condition are to be 

 observed. Moreover, shoots which in one year bore female 

 catkins subsequently bore male catkins, and the reverse change 

 was also noted. Several intermediate forms were recognised. 

 In some, male and female catkins occurred on the same shoot, 

 the former being usually situate below, and the latter above. 

 In the transition region the catkins were sometimes androgy- 

 nous. In other cases all the catkins were androg}nious, and in 

 these the lower part of the shoot was usually male and the upper 

 female, hermaphrodite flowers sometimes being present where 

 the two sexes meet. 



In still other cases most of the catkins were composed of 

 protogynous hermaphrodite flowers, each of the latter con- 

 sisting of a normal ovary surrounded by three to four stamens 

 and bearing at the base two bracteoles. Similar changes of sex 

 have been observed in other species, and here as there nutrition 

 is perhaps an important factor in their determination. 



