101."] Goodspccd: Inheritance in Nicotiana Hybrids 227 



Since the number of plants involved in the above tables is so small, 

 it is, from one point of view, rather useless thus to express the final 

 results of this experiment which has extended over four years and 

 in connection with which such a considerable number of measurements 

 have been obtained. The demand for larg'e F._, and later hybrid gen- 

 erations, to give an approximation of the desired complex ratios, was 

 early met in experiments concerning the inheritance of what may still 

 be called "qualitative" characters and recently the investigation of 

 "quantitative" characters has been attempted upon a similar scale. 

 With reference to certain of the "(jualitative" characters investigated 

 I have no basis for judging the extent and infiuence of the environ- 

 mental factors operative, nor as to the modification of the reported 

 results that would have been produced had careful measurements been 

 made. Data which have been submitted, however, leave no room for 

 doubt in my own mind that investigations on the inheritance of flower- 

 size demand the recognition of certain definite criteria and that the 

 results of such investigations are vitally influenced by inherent as 

 well as externally induced physiological states peculiar to the })lant. 

 Thus it remains to be seen if as many as 800 plants are necessary to 

 establish the validity of an expanded Mendelian notation in P^ of a 

 flower-size hybrid, whether the 40.000 to 80,000 measurements, seem- 

 ingly essential to a fair expression of results, can be accumulated. 

 In other words, the experiment with which this paper deals has been 

 a partially successful effort to measure many flowers on a few plants 

 with the thought that the conception of flower-size would thus be 

 approximately perfect for a few, rather than certainly imperfect for 

 many plants. It is undeniably true that the number of plants is 

 smaller than it should be, and it is perfectly evident that if the flowers 

 on a larger number of plants cannot be correctly measured the attempt 

 is not worth making. Further, it has been ascertained that the gen- 

 eral method of measurement can be greatly improved upon. The 

 attempt to make measurements of flower-size in the field is next to 

 useless where more than fifty plants in a single group are grown. 

 In a flower-size investigation now in progress all the flowers which 

 the plant produces, from the first flower to the flowers on the plant 

 two months later, are picked off and preserved in liquid to be measured 

 in the laboratory. A random selection and careful mea.surement of 

 fifty flowers among all these flowers picked off from each plant should, 

 then, give a fair approximation of the situation with reference to the 

 flower-sizes involved. It is hoped that the parents and three hybrid 

 generations can be grown together during the coming setison. 



