FUNGI AS ANTIGENS AND PLANT PATHOLOGY 423 



fied by such common terms as wilt, scorch, blight, scald, stripe, 

 die-back, shot hole, leak, damping-ofT, chlorosis, stunt, dwarf, 

 drop, russet, intumescence, curl, gall, and scab, all of which indi- 

 cate characteristic symptoms of disease. With the increase in 

 knowledge of changes in cellular structure and function induced 

 by pathogenic fungi, technical terms have been and are being 

 introduced, just as they were in the field of animal pathology. 

 Also there is an increasing tendency among plant pathologists to 

 classify diseases as root-rot diseases, fruit diseases, leaf diseases, 

 seedling diseases, etc., terms analogous to respiratory diseases, gas- 

 trointestinal diseases, skin diseases, etc., as used by the medical 

 worker. There is now a growing tendency to clarify terminol- 

 ogy as belonging to mycology or to phytopathology and to em- 

 ploy terms that are distinctive in each field. 



FUNGI AS ANTIGENS AND PLANT PATHOLOGY 



A very extensive literature on studies of resistance to disease 

 among plants exists and has been recently reviewed by Wingard 

 (1941). Nearly all such studies deal with natural immunity, as 

 opposed to acquired immunity. Experimental evidence that plants 

 may acquire immunity after being "vaccinated" and that anti- 

 body formation results was first submitted approximately 40 years 

 ago. Plant pathologists generally have not reacted favorably to 

 this type of research and have given it little credence for the rea- 

 son that plants lack a tissue system comparable with the circula- 

 tory system in animals. Nevertheless additional reports have ap- 

 peared from time to time of studies that tend to support the possi- 

 bility of acquired immunity in plants. An excellent monographic 

 review of such studies, together with a summary of their own 

 work, was prepared by Carbone and Arnaudi (1930). The "vac- 

 cines" used were either injected into plants or applied to the 

 surface of seeds before planting. Arnaudi (1933) prepared vac- 

 cine of Thielaviopsis basicola from dried powdered mycelial mat 

 or from fresh mycelial mat mixed with sand and triturated in a 

 mortar. These vaccines were applied to the tobacco seed or to 

 the soil with apparent protection of the seedlings. 



Series of studies on immune reactions in plants were conducted 

 by Chester (1932) and by Chester and Whitaker (1933), which 

 snowed that the so-called "plant precipitins" are in fact non- 



