ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 739 



On the Characters of Hybrids.* — C. Correns continues in a number 

 oilpapers his investigations on the relation of the characters of hybrids 

 to ".those of their parents. He points out that although many cases of . 

 supposed dominant characters on renewed examination have been shown 

 to be unsatisfactory, yet a number of cases of absolute dominance still 

 remain. A very good example is that of the hybrid between Hyos- 

 cyamus annum x niger, where the biennial character of the latter parent 

 is completely dominant over the annual character of the first. Also 

 in the hybrid Bryonia alba X dioica the dioecious character of the one 

 parent is completely dominant over the monoecious character of the 

 other. The second case is of great interest as showing that the sex of the 

 plant is not necessarily determined in the egg-cell before fertilisation, 

 otherwise the pollen of B. dioica, which was used, would have had no 

 effect. It shows also that the germ-cells of the dioecious plant possess 

 some male characters, others female, as the dioecious hybrids produced 

 were of both sexes. Correns, in a further paper, points out that the 

 statement of l)e Vries, that Mendel's law holds for the characters of 

 varieties, while the characters of species on crossing become blended, 

 does not hold generally. In a third paper the same worker reviews the 

 various observations on hybrids which have appeared during the year 

 ending in the autumn 1902. 



Colours of Northern Gamopetalous Flowers.j — J. H. Lovell con- 

 cludes his observations on this subject, and arrives at the following con- 

 clusions. The colours of flowers have been determined by their utility 

 rather than by an aasthetic colour-sense in insects, which distinguish 

 between different colours but do not receive greater pleasure from one 

 hue than from another. Any preference they may manifest has arisen 

 from the association of the colours with the presence of food-substances. 

 Conspicuousness, or contrast of the inflorescence with the foliage, has 

 been induced by insects, to which it is of advantage, as it enables them 

 to find nectar-bearing flowers quickly, while it aids the plants in securing 

 cross-pollination. Many colours are better than one, since the flowers 

 are rendered more conspicuous by contrasts with each other as well as 

 with the foliage, and insects are less liable to visit them indiscriminately. 

 The sequence of colours, green, yellow, white, red, purple, and blue, 

 depends upon physiological causes. Plants vary greatly in their capa- 

 bility of forming the different pigments, and the floral colours are 

 correlated with the variability of this function. The primitive colours, 

 green, yellow, and white, have been determined by the nature of the 

 chloroplast and its pigment content ; while red, purple, and blue have 

 arisen as the result of various chemical and physical conditions. 



Botany of the Ceylon Patanas.J— J. Parkin and H. H.-W. Pearson 

 give an account of the anatomical characters of the plants collected by 

 Mr. Pearson on the montane grass-lands of Ceylon, and discuss the rela- 

 tion of these characters to the conditions under which the plants grow. 

 They find that the anatomical characters bear out the result of field 

 observations, in indicating a xerophytic habit. It is of interest to note 

 that these characters are equally well shown in plants from both the 



* Ber. Deutsch. Bot. Ges., xxi. (1903) pp. 195-210; Bot. Zeit... lxi. (1903) pp. 

 110-126. t Amer. Naturalist, xxxvii. (1903) pp. 443-79. 



\ Journ. Linn. Soc. xxxvi. (1903) pp. 430-63 (2 pis.). 



