Hybriden. — Descendenz. 23 



Hurst, Cjharles] C[hamberlain], Mendel's Law applied to 

 Orchid Hybrid s. (Journal of the Royal Horticultural 

 Society. Vol. XXVI. p. 688—695). 



Mendel's formula for the Separation of characters in 

 crosses, first enunciated in 1865 and brought to light again by 

 de Vries early in 1900 is stated as follows: If two distinct but 

 corresponding characters, A and a, be united by crossing and 

 the resulting crosses be self-fertilised, the progeny as regards 

 this pair of characters will separate themselves according to 

 the formula A-J^Aa-f-a i . e. one half will retain the original 

 characters (A and a) and one half wile be intermediate. This for- 

 mula has been extended to 16 genera. Discussing the previous 

 experiments of Mendel, de Vries, Correns and Tscher- 

 mak, the author concludes that as far as the first generation 

 is concerned they are abnormal and exceptional and may for 

 the present be disregarded. The results of experiments in the 

 second generation are however highly important. 



Mendel's formula must be considered apart from 

 Mendel's theory, which will be discussed in a future paper. 

 The author shews that the formula may, with certain modi- 

 fications be extended to the union of specific characters in inter- 

 mediate primary orchid hybrids. 



Having stated the advantages claimed for orchid hybrids 

 for observations in heredity the author enters into a explana- 

 tory discussion of the union of specific characters in intermediate 

 primary hybrids. The term „intermediate" is defined as follows: 

 On the series of forms between A and a, all those that show 

 3 /4 A and more are regarded as A while all that shew Z U a and 

 more are termed a. The remainder, lying between 3 /i A and 

 3 U a are „intermediate". Then follow analyses of the inheri- 

 tance of pairs of specific characters in many distinct hybrids 

 belonging to several genera of Orchids. The results are thus 

 summarised. 



Out of 4,548 pairs of specific characters united by hybridi- 

 sation, 2281 are classed as „specifics" (i . e. as A or a) and 

 2,267 as „intermediates", i . e. approximately one-half „speci- 

 fics" and one half „intermediates". Representing the „specifics" 

 by A and a and the intermediates by Aa we have the formula 

 1141 A+2267 Aa-j-1140 a which is approximately A+sAa-j-a. 



H. H. W. Pearson (London). 



HENRY, Augastine, The wild Forms of the Chrysanthemum. 



(The Gardeners Chronicle. Vol. XXXI. 1902. p. 301—303. 



Fig. 2.) 



The author gives diagnoses of the wild forms C. indicum 

 L., C. morifolium Ramat. var. genuinum Hemsley and C. mori- 

 folium Ramat. var. graclle Hemsley and states that the last 

 variety may be subdivided into two subvarieties A and B. A is 

 a small plant about 1 foot high and occurs wild in North China; 

 B reaches 2 ft. in height and is a native of Japan. Other wild 



