examination of the genes themselves would 

 circumvent this difficulty. Although it is impos- 

 sible to do this at present it is possible to 

 examine differences in the presumed primary 

 gene products, the enzymes controlling specific 

 reactions. The assumption made here is that 

 the greater the number of enzyme systems held 

 in common by different populations, the closer 

 their phylogenic relationship . 



APPLICATION OF CHROMATOGRAPHY 



Literature in this new field of systematic 

 chromatography is rather sparse but surpris- 

 ingly diversified. Rather than present the work; 

 in chronological order, I have chosen to take it 

 up phylogenically . 



Three groups of plants have been investi- 

 gated. Buzzati-Traverso (1953) chromato- 

 graphed varieties of both the tomato, Solanum 

 lycopersicum L., and the muskmelon, Cucumis 

 melo L. Selle (1954 a, b) worked with varieties 

 of the sour orange, Citrus aurantiu m L . The 

 tissues used were pollen, root tips, leaf ex- 

 tracts, and root bark. The compounds exam- 

 ined were ninhydrin positive and fluorescing 

 materials. In all cases only the chromatograph- 

 ic pattern was examined, but this was sufficient 

 to separate the varieties under scrutiny. 



Among the animals, seven species of 

 land snails were investigated by Kirk, Main, 

 and Beyer (1954). The chromatographic pat- 

 terns of ninhydrin positive and fluorescing 

 compounds extracted from foot muscle tissue 

 were examined and the seven species could be 

 distinguished. Four of the species were of the 

 same genus. Three of these species had strik- 

 ingly similar patterns. 



Ball and Clark (1953) and by Micks and Ellis 

 (1952). The several species had distinct amino 

 acid patterns which were fairly constant irre- 

 spective of the area in which the mosquitoes 

 were collected. At the same time it was shown 

 that there was a change in the free amino acid 

 complement which accompanied metamorphosis. 



Williams (1951) and coworkers have been 

 using the body fluids of humans for chromato- 

 graphic analysis and have quantitatively 

 analyzed a wide variety of compounds . The 

 object is the biochemical characterization of 

 both the population and subpopulation . In this 

 case, a suggested subpopulation is composed of 

 alcoholics having a unique population of com- 

 pounds which may be associated with alcoholism . 

 Once the association is made, it will be neces- 

 sary to show whether an array of compounds is 

 associated with the cause of alcoholisms (genetic) 

 or whether the array is the result of alcoholism 

 (environmental) . 



Dannevig (1955), working with fish, has 

 shown that some 23 species of fish have differ- 

 ent ninhydrin -positive compound patterns. 

 Likewise, Buzzati-Traverso and Rechnitzer 

 (1953) have shown that various species of fish 

 can be separated on the basis of their chroma- 

 tographic patterns . They state that the closer 

 the two species are phylogenetically, the more 

 similar are the chromatographic patterns. 

 FarrisJ/ made a study of the Pacific sardine, 

 Sardinops caerulea , with respect to environment- 

 ally induced variation in the chromatographic 

 pattern, and found that the pattern could be 

 changed quite significantly with respect to at 

 least two components of the free amino acid 

 complex. This change was correlated with the 

 relative fatness and with the diet of the fish. 



Utilizing essentially the same technique, 

 Hadorn and Mitchell (1951) and Buzzati-Traver- 

 so (1953) chromatographed the bodies of 

 Drosophila melonogaster, and were able to dis- 

 tinguish various mutants. In some cases the 

 heterozygotes could be distinguished from the 

 homozygotes. Changes in the pattern were also 

 observed during metamorphosis. 



Culicid mosquitoes were examined for 

 free amino acids by Clark and Ball (1951, 1952), 



DISCUSSION 



It is apparent that this work is still in an 

 exploratory phase. A rigorous evaluation of 

 the method is very difficult because of the pauc- 

 ity of data . On theoretical ground, systematic 

 chromatography holds great promise. The 

 amount of material is practically unlimited. 

 1/ Ms. "Diet induced variation in the free 

 amino acid complex of Sardinops caerulea" . 



36 



