124 



tacks the stem, the plant suffers greatly, 

 sometimes dries out entirely. 



Rust seems to me to bear much re- 

 semblance to smut. Smut transforms 

 the organs of fructification to a black 

 powder; rust transforms the parts be- 

 low the epidermis or outer covering to 

 a brown powder. At all events I believe 

 that the cause of both these diseases is 

 one and the same. As remedies for rust 

 the farmers suggest the same as used for 

 smut. 



LOWER PLANTS, DISEASES, AND MEDICINE 



Class 5-Galls 



Galls is the name applied to knobs 

 and excresences due to the stings of 

 various insects. The so-called ergot 

 (Clavus) is no other than a form of 

 this disease. It comes about in a simi- 

 lar way: Thrips Physapus Linn, attack- 

 ing the tender rye kernels and laying 

 its eggs in them, the kernels develop 

 over the husk, become blackish, lumpy, 

 internally fungous and containing a 

 rotten, brownish powder. 



QUESTIONS 



1. When was Fabricius born? 



2. What kind of a plant scientist does he 

 best resemble? 



3. Would you say that during the 200 

 years intervening between his birth and 

 the present day, most of the prob- 

 lems of plant disease have been solved? 

 Discuss this with your instructor. 



4. Try to find out what are some of the 

 unsolved problems of plant pathology. 



5. Did Fabricius consider this field well 

 developed in his day? 



6. Which seemed more important to 

 Fabricius as causes of disease, the in- 

 ternal or the external ones? 



7. Compare in a paragraph or two the 

 modern theory of the cause of smut 

 with that held by Fabricius. Use corn 

 smut as an example. 



8. Do the same with rust, using wheat 

 rust as an example. 



9. What is ergot of rye? 



N.B. Fabricius was born in 1745 and died in 1808. His observations were 

 a valuable contribution to knowledge concerning plant diseases. 



