368 Tricotylous Races. 



a simple method of searching for such anomalies. Fas- 

 ciations are so common in nature and in the garden that 

 special means for obtaining them are not required; but 

 twisting is much rarer and ordinarily it is only by a lucky 

 chance that we meet with an instance of it.^ If we wish 

 to become independent of this chance we must have re- 

 course to the culture of variations of cotyledons, because 

 such will offer a greater likelihood of furnishing the de- 

 sired anomaly than other examples of the same species. 

 In the first, or at least in the second, generation we may 

 count on finding them, if the extent of the experiment 

 is sufficiently great, and once obtained, they can easily 

 be further improved by ordinary selection. A single in- 

 stance will suffice. ]\IoRREN found a very fine specimen 

 of twisting in Dracoccphaluui spcciosnm in a meadow not 

 far from Liege, ^ and wdien I read his description I be- 

 came extremely anxious to investigate such a case of 

 torsion in this species, or at any rate in this genus. For 

 this purpose I selected Dracoccphahun moldavicuin, 

 which, being an annual, seemed more suitable. In the 

 spring of 1892 I selected a single hemi-tricotylous seed- 

 ling found in a sowing of commercial seed (a little less 

 than 20,000 seedlings), and from this bred a race wdiich 

 in the first year exhibited nothing remarkable but pro- 

 duced fasciations in the second year and traces of twist- 

 ing in the third, and finally, in the fourth, some very 

 fine instances of spiral torsion. One of these had the 

 whole main stem transformed into a screw (Fig. 74). 

 Fortunately in such experiments, the aim can be attained, 

 as a rule, in a much smaller number of years. 



^Monographic dcr Zzcan^sdyeJiun^cu. Prixcsheim's Jahrb. f. 

 wiss. Bot., Vol. XXIII, p. ii6. 



""Bull. Acad. Roy. BcJg., Vol. XVIII, p. zy. 



