SEROLOGY AND SYSTEMATICS 



79 



troughs are cut into the agar along the electrophoretic track between 

 each sample, and antiserum is poured in (Fig. 5-2). The antigens and 

 antibodies diffuse into the agar, and when they meet, corresponding 

 antigens and antibodies form stabilized precipitates in the shape of 

 arcs which may be detected by appropriate methods. 



A recent botanical study involving the immunoelectrophoretic 

 technique is that of Gell, Hawkes, and Wright (1960) on the genus 

 Solanum. They studied the gel diffusion patterns of fifteen Mexican 

 and twenty-two South American species of this genus. Since the anti- 

 sera were relatively ineffective in distinguishing the South American 

 species, only the fifteen Mexican species will be discussed. The latter 

 species are arranged into seven series according to Hawkes' sys- 

 tematic treatment. (He divided the tuberous solanums into seventeen 

 series, some of which are listed below.) 



HI. Morelliformia 



IV. Bulbocastana 



V. Cardiophylla 



VI. Pinnatisecta 



XII. Demissa 



XIII. Longipedicellata 



XIV. Polyadenia 



S. morelliforme 



S. bulbocastanum 



S. cardiophyllum 

 S. ehrenbergii 

 S. sambucinum 



S. pinnatisectum 

 S. Jamesii 



S. demissum 

 S. guerreroense 

 S. semidemissum 

 S. spectabile 

 S. verrucosum 



S. polytrichon 

 S. stoloniferum 



S. polyadenium 



In the preparation of the extracts from the tubers the crude 

 juices were adjusted to yield a protein concentration of 0.5 per cent. 

 Antisera were prepared from rabbits. 



