SEROLOGY AND SYSTEMATICS 33 



In recent years there has been considerable interest in a modi- 

 fied serological method using relatively crude plant extracts to dis- 

 tinguish human blood types. Although an important motivating 

 factor in this work is a rather practical consideration, namely, the 

 commercial application of specific plant agglutinins in blood typing, 

 there are in addition a number of intriguing problems of a fundamen- 

 tal nature involved (Boyd, 1960). Although this work is not widely 

 known, even now, the first report of the existence of a plant agglutinin 

 manifesting some degree of selectivity was made as early as 1888 

 when Stillmark noted that an extract from the seeds of the castor 

 bean {Ricinus communis) agglutinated the red blood cells of animals 

 selectively. Although occasionally some minor work was devoted to 

 plant agglutinins, for the most part the subject was ignored until 

 1948 when Renkonnen at Helsinki revived interest in plant agglutinins 

 with a survey of ninety-nine legume species, six of which showed 

 definite affinity for either A or blood types. Subsequently, nu- 

 merous investigations have disclosed a large number of legume species 

 which agglutinate red blood cells, sometimes with no antigenic speci- 

 ficity but frequently with definite specificity. No knowledge is 

 available concerning the botanical function of the agglutinins which 

 are usually, but not always, obtained from the seeds. By 1955 per- 

 haps a thousand species of plants had been screened, and an over- 

 whelming proportion of the species disclosed to be producers of 

 "specific" agglutinins were in the family Leguminosae. The relevance 

 of this work to biochemical systematics lies in the question of whether 

 such investigations can disclose any meaningful patterns of distribu- 

 tion of agglutinins among the plant species. 



Following the work by Renkonnen, selected examples of some 

 important early surveys are those of Boyd and Reguera (1949) who 

 studied 262 species from sixty-three families and Krupe (1953) who 

 studied 167 species in the Leguminosae and, in addition, ninety-four 

 different varieties of lima bean {Phaseolus lunatus). Krupe, for 

 example, found some genera such as Lathyrus and Phaseolus which 

 showed quite consistent agglutinin activity; that is, a large propor- 

 tion of the species were active. Other genera, for example, Caragana, 

 showed wide species differences. Species which specifically favored 

 certain blood groups were recognized; for example, Lotus tetragono- 

 lobus favored blood type O; Vicia cracca and Phaseolus lunatus 

 favored blood type A; and Sophora japonica and Coronilla varia 

 favored blood type B. By far the most comprehensive survey and 

 general study of plant agglutinins, however, has been that of Makela 

 (1957), a student of Renkonnen, who studied 743 species of the 

 family Leguminosae, including 165 genera. Thirty-seven per cent of 



