SECTIONAL TRANSACTIONS.— K. 427 



cytology, ecology, and genetics. The advantages and dangers of the 

 new outlook. 

 (4) The practical aims of the Association for the Study of Systematics in 

 Relation to General Biology. 



Mr. W. J. C. Lawrence. — The genetics and taxonomy of some garden 

 plants (10.30). 



As a result of recent biochemical and genetical investigations on flower 

 colour in a number of species, the basis of floral pigmentation is now clear. 



(i) Biochemical. — The three primary classes of pigmentation are : 

 (i) plastid (pale yellow to orange) ; (2) anthoxanthin, i.e. flavones and 

 flavonols (ivory to deep yellow) ; (3) anthocyafiins (reds and blues). A true 

 ' white ' lacks all three kinds of pigment. The anthocyanins may be further 

 divided into three main types — pelargonidin, cyanidinin and delphinidin. 

 The wide range of flower colours results from the combination in various 

 proportions of the different pigments. 



(ii) Genetical. — The role of the genes in pigment production is as a rule 

 highly specific, a given gene acting upon a particular pigment, either 

 quantitatively (increase or decrease in production) or qualitatively (modi- 

 fication, within the class, of the nature of the pigment). 



Experiments on three garden plants, Streptocarpus , Delphinium Ruysii 

 and Dahlia variabilis, demonstrate how the origin of species may be eluci- 

 dated from combined cyto-genetical and biochemical analysis. The hybrid 

 derivatives show, chemically, recombination of the pigments of the parent 

 species. The methods employed enable rapid and precise comparisons to 

 be made between species, thus providing the taxonomist with a further 

 measure of the relationship and evolution of species. 



Prof. J. R. Matthews. — Specific segregation and distribution (ii.o). 



Examples are given of closely allied species which may be held to have 

 been derived from a common ancestral stock but which, among other 

 features, are distinguished by a different geographical range. In the 

 absence of genetical studies the origin of these related forms is still obscure, 

 though cytological observations are available for some of them. Little 

 attempt has yet been made to formulate views regarding the influence of 

 isolation. 



Dr. T. J. Jenkin. — The relation betzveen genetics and systematics (i 1.30). 



This question is discussed primarily as it applies to some of the non- 

 cereal grasses. 



In these grasses, the paucity of well-defined and easily observed morpho- 

 logical characters makes the work of the systematist, and that of the geneticist, 

 very difficult. This may have led the systematist to attach undue importance 

 to those characters that are easily observed, so that detailed classification 

 is sometimes based upon somewhat obscure and possibly inconstant 

 characters. 



The geneticist is not always a good systematist, neither is the systematist 

 always an experienced geneticist, so that clearly collaboration is greatly to 

 be desired. This applies equally to the question of supposed natural 

 hybrids, but perhaps here the plant breeder and the cytologist are more 

 important than the pure geneticist. 



The artificial production of inter-specific and inter-generic hybrids will 

 affect not only the position of the supposed natural hybrids, but also the 



