200 ROLLINS 



numerous, or difficult to handle. However, caution in interpreting the sig- 

 nificance of chromosome counts is fully justified. 



The work on chromosome morphology is tedious and difficult in many 

 plants, and in many others there is little or no morphological differentiation 

 within the chromosome complement of a given species. In difficult groups, 

 it has often not been profitable to attempt to work with chromosome mor- 

 phology for taxonomical purposes. However, in some plant groups, where the 

 chromosomes are sizable and dissimilar and there are karyotypic differences 

 between species, marked results have been achieved. We may confidently 

 cite the major role played by chromosome work, in the monographic studies 

 of Crepis by Babcock (1947) and his coworkers, to demonstrate this fact. 

 Here, chromosome morphology combined with chromosome number was of 

 considerable importance both in the genetical and in the taxonomical phases 

 of the study. Another major work in which chromosome studies played an 

 important role is that of Goodspeed (1954) and his collaborators on the 

 genus Nicotiana. Of classical interest in this connection is the work of 

 Sakamura (1918) on Triticum, who greatly aided in clarifying the taxonomy 

 of the wheats through chromosome studies. 



We feel impelled, by the numerous overstatements of Darlington (1956) 

 as to the importance of the chromosomes for all phases of botanical study, 

 to suggest that the key to all the truths regarding plants does not lie in the 

 karyotype. Here, as in other features, the facts one finds are most likely 

 to show their greatest importance when properly intermeshed with many 

 other facts from various sources. To the taxonomist above all others it is 

 essential that the total evidence regarding a given plant be admitted and 

 evaluated. 



THE ROLE OF EXPERIMENT 



The early work in taxonomy was observational and descriptive. But as the 

 science of botany developed, there was a long succession of taxonomists who 

 manipulated their plants to discover new facts. This was especially true in 

 research connected with reproduction and the functioning of the floral mecha- 

 nism. These botanists were the forerunners of the experimentalists who de- 

 veloped some of the present-day botanical disciplines where experimental 

 procedures are preeminent. As the subjects of plant physiology and genetics 

 developed, taxonomy was for a time diverted away from experimental areas 

 of botany. However, it has not remained so, and the trend during recent years 

 has been toward the utilization of experiment along with other procedures in 

 elucidating the facts of relationship and classification. Experimental taxonomy 

 has indeed become an increasingly important aspect of the work in taxonomy 

 as a whole. 



The type of experimentation differs, depending upon the objectives. The 

 most frequent are undoubtedly those associated with genetics and cytology, in 



