tN THE tropics : m. 179 



The most interesting event of the year which has elapsed 

 since that account was written has been the publication by 

 Correns of Mendel's letters to Nageli, written between 1866 

 and 1873. These illustrate in a remarkable way Mendel's 

 astonishing activity as a hybridizer, and show that his 

 publications on peas and on Hieracium represent only a 

 small section of the experiments he had in hand — experiments 

 which confirm the conclusions drawn from the study of pea 

 crosses by similar observations on a wide range of different 

 plants. 



We find moreover that the idea — recent subject of much dis- 

 cussion — that sex may be a Mendelian phenomenon was present 

 to Mendel himself, having been suggested by the existence 

 of the proportion 151 female : 52 male plants in Fi from a 

 cross between Lychnis diurna and L. vespertina. 



Correns points out in an appendix that this particular case 

 cannot indicate the existence of simple dominance and of Men- 

 delian segregation. He contends further that the " Anlagen " 

 for the separate sexes are never fully segregated, but it seems 

 doubtful whether he has successfully excluded all possible 

 explanations involving a Mendelian segregation of the 

 sexes. 



The second report to the Evolution Committee of the Royal 

 Society, by Bateson, Miss Saunders, Punnett, and others, 

 though published in the present spring, contains complete 

 records of their work only to the end of 1903, with some 

 reference to that of 1904. 



The account of the inheritance of characters of the comb in 

 fowls raises points of considerable interest. Put very briefly 

 the facts are as follows : — 



" Rose " comb (r) behaves as a simple Mendelian domi- 

 nant to single comb (s). 



" Pea " comb (p) crossed with single does the same. 



r crossed with p gave a comb of characteristic appearance 

 (rp), known as " walnut" and similar to that of the Mala} 7 

 breed. 



