1929] 



Bah cock-Clausen: Meiosis in Crepis 



417 



Only iroii-acetocarmine smears from Carnoy-fixed material have 

 been used in the investigation of this hybrid, also, because no differ- 

 entiation was obtainable in the imbedded and sectioned material. 



TABLE 5 



Distribution of Chromosomes in Homotypic Anaphase of 



C. taraxacifolia X tectorum Fi 



^, means that the nuclear plate in question could not be counted. 

 A and .4j, B and Bi are corresponding nuclear plates. 



TABLE 6 



Number of Chromosomes in 48 Homotypic Anaphase Nuclei as Calculated 



FROM Table 5 (Direct Observation) 



The type of conjugation described in the Crepis hybrids, with a 

 fairly wide range of variation in the amount of pairing between the 

 chromosomes, has been observed by the junior author in a number 

 of Viola hybrids. Apparently in these cases some affinity must exist 

 between all the partly homologous chromosomes as they sometimes all 

 pair. Still the affinity must be somewhat weaker as the chromosomes 

 often fail to conjugate. These cases of partial affinity between the 

 chromosomes are intermediate between two extremes. On one hand 

 we have hybrids in which the affinity between the parental chromo- 

 somes is so slight that they will never conjugate, as, for instance, in 

 the hybrids Nicotiana BigeJovii X suaveolens and Bigelovii X gluti- 

 nosa (Goodspeed and Clausen, 1927) and Eaphanus X Brassica (Kar- 



