108 



The determination, of varieties of com is the most difficult as they 

 are very numerous ; and it is necessary, very often, to distinguish varieties 

 of which the difference is but slight, or rather where it is only biological. 

 The determination of the varieties of wheat is ca.rried out by the observa- 

 tion of different degrees of colouring of grains (pericarp) produced after 

 six hours by the preparation oxybenzine-mercury-chloride (mercurial 

 chlorophenol) No. 778 in a 1 per cent, solution after having previously 

 been steeped for 24 hours (Pieper method). I have followed this method 

 in establishing the difference of 61 varieties, mainly of Czecho-Slovak origin,, 

 and I have been able to ascertain that the differences were considerable- 

 Steeping in distilled water showed itself to be the best. I have also- 

 ascertained that the colouring of coleoptiles of shoots of wheat is a very 

 valuable method in laboratory work. 



Of these 61 varieties that I have observed, the coleoptile was as 

 follows : — - 



Coloured brown-red - - - 11 



Without colour 33 



Some grains only coloured 17 



As regards wheat grain it is as well to know also the length of the hairs 

 of the grains and the number of rows of thick membrane cellules similar 

 to the epidermic cellules of the central layer of the pericarp (Kondo). 



If it is desired to discern the " a " and " c " types of leaning barley 

 {H. dist. nutans) it is necessary to ascertain microscopically if the hairs 

 are of one (type "a") or rather of two or even several cellules (type 

 " c "). If barley is concerned it is also wise to ascertain the contours 

 of the grain in the lateral position, and when 6-row varieties of barley 

 are concerned it is desirable to establish the greatest width of grain 

 (Holmgaard). The best determination of oats is made on the exterior 

 of the grain and what aids us here is also the colouring of the first leaves 

 of the shoots (Holmgaard). 



I have only enumerated some of the more remarkable and more 

 frequently used signs. If varieties have to be determined on the fields 

 all characteristics must be ascertained and a detailed description of them 

 compiled. 



To facilitate determination still niore, it is not only necessary to have 

 collections of seed, ears, tubercles, roots and collections of leaves and 

 inflorescences, but also to establish trial gardens of varieties. The 

 material to be observed must be taken, it is true, directly from the plant 

 breeders, and it is necessary to cultivate the plants normally with a view- 

 to their having a normal appearance. To know thoroughly the biological 

 qualities of plants, trials should be made several years in succession. 



It is desirable that the Eiu'opean Seed Testing Association should 

 extend the unification and studies of methods and usual standards 

 to the determination of identity and purity and, eventually, to the quality 

 of varieties. 



It would consequently be necessary that exchange of matters observed 

 in the variety trial gardens should be reciprocal among the various 

 institutes, and that there should exist among them a sort of mutual 

 communication of descriptions of different varieties, as is already the 

 case among the administrations of botanical gardens. 



(The full paper in German will be found on pp. 204-215.) 



A discussion followed on the various methods of identification-^ 

 of different species and varieties, viz., biological, biometrical, 

 morphological, pathological, physico-chemical, and what the, 

 Polish delegate aptly said might be described as the BertiUon. 

 method. 



