Morphologie etc. — Varietäten etc. 291 



mination two male and two feraale plants. The structure of the 

 thallus and the sporophyte is identical with that of the Riccias with 

 the exception of the adhering spore tetrads and the pegless rhizoids. 

 These structural differences seem insufficient to exclude Thallocar- 

 pus from the Marchantiales. Jongmans. 



Saunders. E. R., A suggested explanation of the abnor- 

 mally high records of doubles quoted by growers of 

 Stocks [Matthiola]. (Journ. Genetics. V. p. 137—143. 1915.) 



The author has published a considerable amount of evidence 

 to show that the actual Output of doubles among strains of Stocks 

 now in cultivation does not exceed on the average 56—57 percent 

 or possibly 53—54 percent. 



It is pointed out that a percentage considerably higher than 

 this is frequently quoted in current Aorists' lists, rising to as high 

 as 80 percent. 



In this paper there are recorded in detail the experiments 

 which led to the conclusions that doubles develop on the whole 

 raore rapidly and vigorously than the Singles: and that where the 

 period of development is sufficiently prolonged, selection based on 

 this difference can be used as a means of securing a higher Pro- 

 portion of doubles in the flower beds than corresponds with the 

 actual output from the parent plants. 



Thus by carefully keeping all the plants of a sowing and 

 dividing them into „more vigorous" and „less vigorous" halves, the 

 Proportion of doubles and Singles in such a group were found to 

 be as follows: 



More vigorous group contained 170 doubles to 96 Singles. 



Less vigorous group contained 136 doubles to 124 Singles. 



The proportion of doubles to Singles among the most vigorous 

 of the „more vigorous" half is of course considerably higher. 



W. Neilson Jones. 



Saunders, E. R., On the relation of half-hoariness in Mat- 

 thiola to glabrou.sn ess and füll hoariness. (Journ. Gene- 

 tics. V. p. 145—148. 1916.) 



The author's earlier work in this direction may be summarised 

 as follows: 



1. Since some true breeding white Stocks, when crossed, give 

 rise to coloured offspring it is concluded that the combination 

 of two factors (indicated by C and R) is required to producecolour. 



2. Similarly, from the fact that it is possible to obtain a hoary 

 F x from two coloured glabrous strains it is concluded that the 

 combination of two factors (indicated by H and K) is necessary to 

 produce hoariness. 



3. A further point of special interest is that the hoary character 

 due to the presence together of H and K is not manifested unless 

 the colour factors C and R are also present. 



4. The factorial composition of the hoary and glabrous types 

 are therefore as follows: 



a) Hoary types: will contain C, R, H and K. 



b) Coloured glabrous strains: mav contain CRH, CRK or 

 only CR. 



c) White or cream glabrous strains: may contain any 



