582 Varietäten, Descendenz, Hybriden. 



occasionaJly obtained "mutants" with large petals and short styles. 



It seems that the mutation phenomena in O. Lamarckiana are 

 due to a disturbed or unstable condition of the germ plasm, which 

 has probably resulted from crossing in the ancestry. It is not pro- 

 bable, however, that the retrogressive mutants, such as O. nanella 

 and O. lata are due to simple hybrid Splitting of types which entered 

 into the ancestry. The chromosomal irregularities during meiosis 

 (maturation), which the present writer described , furnish a possible 

 basis for the occasional appearance of retrogressive mutants in each 

 generation. 



Certain cases, however, can not be explained as the result of 

 hybrid Splitting or loss of characters, and show that O. Lamarckiana 

 has experienced a more general disturbance of its germ plasm. Of 

 these cases, O. gigas with its tetraploid number of chromosomes, 

 probably originated through a germinal change at another point in 

 the life cycle. A number of tetraploid species among angiosperms 

 and ferns have probably originated in an analogous manner. Also 

 0. ruhricalyx, a mutant from O. ruhrinevvis showing a large positive 

 Variation in red pigment productions, is not likeh'^ to have origina- 

 ted through a new chromosome combination, but more probably 

 through some quantitative cytoplasmic change. 



Mutation in 0. Lamarckiana, therefore, appears to be a condi- 

 tion of germinal instability and not a simple process of hybrid 

 Splitting, although this condition of instability has probably been 

 brought about through previous crossing in the ancestry. There is, 

 however, at present no satisfactory evidence that O. Lamarckiana. 

 has originated from a Single cross. 



Mutation, whether or not always preceded or accompanied by 

 crossing (of which it is probably a result), will thus account for 

 much species formation, and for the polymorphism of many genera. 

 That it will account for the larger evolutionary trends and for 

 many adaptations, remains to be shown. Jongmans. 



Harris, J. A., On the formation ofcorrelation and con- 

 tingency tables when the number ofcombinationsis 

 large. (The American Naturalist. XLV. p. 566—571. IQll.) 



The purpose of this note is to point out a method of preparing 

 correlation tables where the number ofcombi-nations is large. Where 

 the number of individuals in an array is very small the method 

 presents no very marked adventages, but when the arrays are 

 large it may be very useful and its ränge of applicability very wide. 



For instance, one of the tests of the genotype theory of inhe 

 ritance is to compare the correlation between parents and offspring 

 with that between the parents co-fraternity and the offspring in a 

 Population of self-fertilizing or vegetatively propagating individuals, 

 The correlation surfaces are very easily prepared. Two seriation 

 tables, one for the arrays from which the individual parents were 

 drawn and one for the offspring arra5^s corresponding to each pa- 

 rental fraternity, are prepared. The first table is cut into Strips by 

 columns, passed strip by strip over the offspring seriation table, 

 the frequencies which are in juxtaposition are multiplied together 

 and summed simultaneously, and the resulting ^otals entered in the 

 proper compartments of a correlation table. This va^y be called an 

 ascendant-descendant correlation surface. It includcs both „paren- 

 tal" and „avuncular" relationships. The „avuncular" relationship is 



