Descendenz und Hybriden. 137 



When Fl is purple the coloured class consists of purples and 

 reds. In both sweet peas and Stocks the ratio is 27 purple, 9 red, 

 28 white, composed thtis : 



27 : 9 : 9 : 9 : 3 : 3 : 3 : 1 



28 



The purples are due to the presence of a „blue" factor B, alle- 

 iomorphic to b, its absence. Unless C and R are both present, 

 B cannot be perceived without breeding tests. The three pairs, 

 C, c, R, r, B, b, by entering into all possible combinations according 

 to the simple MendeHan System, give the results observed. 



This scheme takes no account of the sub-classes which some- 

 times occur in both purples and reds. Several of these are merely 

 superposed on the primary classes, while others are more complex 

 and require further analysis. The distribution of the colours shows 

 further complications when some coloured strains were introduced 

 as original parents. 



„Reversion" is thus seen to be a simple and orderly pheno- 

 menon, due to the meeting of factors belonging to distinct though 

 complementary allelomorphic pairs, which at some moment in the 

 phylogeny of the varieties have each lost their complement. 



Pollen-characters in Sweet Peas. — Gametic coupling of a novel 

 kind exists in this case. The whole generation in Fa consists of 

 3 long: l round. The whites taken alone alsot are 3 long: 1 round. 

 But in the purples there is a great deficiency of rounds, while in 

 the reds they are greatly in excess. This result indicates that there 

 is a partial coupling of the long pollen-character with the factor B, 

 and a corresponding coupling of round pollen with b. This peculi- 

 arity onlv occurs in families which contain both purple and red 

 members. The gametic Output of Fi in these cases is approximately 



7AB+ 1 Ab+laB + 7ab 

 where A is long, and a round poilen. This arrangement gives a 

 close approach to the observed figures: 



Purple. Red. White. 



Cannarella, P., Ricerche intorno ai limiti di variabilitä 

 dell'An'sarum vulgare Targ. (Nuovo Giorn. bot. Ital. XIL 

 [1905.J No. 3. p. 328.) 

 Ce travail est une etude faite sur plus de 800 spdcimens 

 d'Arisaru/n vulgare Targ. relativement ä ses limites de variabilitä. 

 Les fleurs mäles ont leur plus grande frequence (34) observde sur 

 50 individus, tandis que les fleurs femelles varient entre 1 et 16 

 avec la moyenne de 4, observ^e sur 137 individus. En reunissant 

 tous les cas de frequence en coordonndes cartdsiennes, on 

 obtient une courbe trfes-irreguliere. Les anomalies des fleurs mäles 

 et des fleurs femelles sont tres-variables et la disposition des fleurs 

 femelles sur la spathe est aussi variable. Enfin quoique les fleurs 

 mäles soient diffdrement distribu^es par rapport aux fleurs femelles, 

 on peut conclure que, si les premiöres diminuent, les secondes le 

 fönt aussi, et rdciproquement. Ce travail se termine par quatre tables 

 statistiques comparatives. Pavolini (Florence). 



