MISCELLANEOUS COMPOUNDS 293 



sponses to one or more antibiotics has been characteristic of different 

 species or strains of this genus, and striking differences have been 

 noted between certain taxa which are quite similar morphologically. 

 Thus, cryptic physiological (or biochemical) differences may be dis- 

 closed, despite morphological similarity. 



A related approach is that of investigations of toxic plant 

 substances which affect higher animals. It has already been noted that 

 cyanogenetic glycosides of the genus Lathyrus produce a disease in 

 livestock known as lathyrism (Selye, 1957). The toxicity of certain 

 plants has led to extensive chemical investigations which have dis- 

 closed information of probable systematic significance. Surveys such 

 as those of Duncan et al. (1955, 1957) may therefore prove to be of 

 indirect value through disclosing new toxic species. The information 

 will either supplement existing knowledge to the extent that a sys- 

 tematic pattern is either exposed or denied, or it will encourage 

 further chemical investigations of a group not previously known to 

 demonstrate toxicity. A high proportion of the toxic substances dis- 

 closed by such methods are probably alkaloids which could be assayed 

 directly with much simpler techniques. It thus appears appropriate 

 to avoid an exaggeration of the potential of screening methods of all 

 sorts since it is doubtful that any taxonomic conclusions of conse- 

 quence can be drawn from the survey directly. 



Some additional unusual approaches, which in effect are 

 vicarious surveys, may be noted. For example, the use of arrow poisons 

 by natives of the Americas has disclosed a much larger number of 

 plant species which produce toxic substances than is generally known. 

 Curare, from Strychnos toxifera (Loganiaceae) and other Strychnos 

 species is well known, but Cheney (1931) found that species represent- 

 ing twenty-one different families were utilized by one or another 

 Indian tribe. In addition to the Loganiaceae the family Ranunculaceae 

 was well represented. Several species of Ranunculus and Anemone 

 were employed as were those of Aconitum and Delphinium. The toxic 

 principles in most cases are believed to be alkaloids. Cheney con- 

 cluded that the Indians of a given area had succeeded in discovering 

 and utilizing the most poisonous species indigenous to the area. 

 Furthermore, they recognized the plant part in which the toxic 

 principle was most concentrated and the stage of development which 

 gave the best yield. Similarly, the use of plants as fish stupefication 

 agents by the Tarahumar Indians of northwestern Mexico has dis- 

 closed numerous toxic plant species. Pennington (1958) lists plants of 

 thirteen different families which were used as stupefying agents, and 

 in these cases the toxic principles were either unknown or apparently 

 belonged to classes such as alkaloids, cyanogenetic glycosides, or fre- 

 quently saponins (for example, in Agave schottii). 



