MUTATIONS, VARIATIONS, AND RELATIONSHIPS OF THE OENOTHERAS. 3 



of the methods emploved in the stimulation of ovaries was given in a lecture 

 at the Woods Hole Marine Biological Laboratory, July 20, 1906, in conjunction 

 with which derivatives thus obtained of the second generation in Raimannia 

 and of the first of 0. biennis were exhibited. The results of Dr. Shull's 

 statistical inquiries were presented before the Botanical Society of America at 

 New Orleans, January 3, 1906, and various notes have been presented before 

 other societies. 



PEDIGREE-CULTURES OF OENOTHERA LAMARCKIANA. 



Arrangements were made by which seeds were obtained from four separate 

 individuals, purely fertilized with their own pollen. This was done by apply- 

 ing the pollen to the pistil of the same flower or of another flower of the same 

 plant. All sowings were made in earthenware pans, 30 by 30 cm., filled with 

 soil sterilized in an autoclave as in previous cultures, and when sufficiently 

 developed the seedlings were removed, to be transplanted or discarded, as 

 the conditions of the experiments demanded. The cultures are given under 

 the key-numbers by which they were designated in the journal of the experi- 

 mental garden. 



A. I. 0. — -A packet of seeds which was given the foregoing designation, 

 which had bsen harvested in Amsterdam in 1901, and was obtained directly 

 from Professor Ds Vries. The sowing was made in August, 1904, and the 

 small rosettes were inspected by Professor De Vries late in September, 1904, 

 and he kindly assisted in the identification of a few of the mutants included. 

 Some confusion in the record makes it impossible to give the exact census of 

 the culture, but it comprised between 500 and 600 seedlings, among which 

 26 mutant derivatives were identifiable, and, so far as possible, two represent- 

 atives of each type were transplanted to the experimental garden in May, 

 1905, coming into bloom about 60 days later. 



The authors have not had the opportunity of inspecting living specimens 

 of all of the mutants which have appeared in Amsterdam and which have 

 been described by Professor De Vries, and of the 9 forms seen but 5 have 

 been conclusively recognized. Of these, O. oblonga was represented by 12 

 individuals, constituting 46 per cent of the total number of mutants. The 

 average frequency of this type among the mutative progeny is i per cent, or 

 20 per cent of the mutants, although in one series De Vries found 176 ohlongas 

 among a total of 334 mutants derived from a culture consisting of over 14,000 

 individuals. In this instance oblonga constituted nearly 53 per cent of the 

 mutants or 1.25 per cent of the entire progeny. (In De Vries, 1905, p. 545, 

 the proportion of oblonga in cultures is given as 10 per cent, which is a mis- 

 print for I per cent.) 



In the New York culture under discussion, lata was represented by one 

 individual, nanella by one, albida by two, and gigas by one. Of these, the 



