ARKIV FÖR BOTANIK. BAND. 1. 145 



my readers against supposing that the fungous mycelia are 

 identical, independent of their origin. I have pointed out, both 

 in 1897^ and in 1902,- that the difference in the periods of 

 incubation we meet with after infection b}^ different spore- 

 forms of one and the same species of fungus impels us to 

 caution and makes us suspect that the nature of the myce- 

 lium cannot be quite the same in the different instances. 

 I have at the same time also urged the importance of a 

 more detailed examination of the mycelia which have diffe- 

 rent modes of origin. 



I have expressed this opinion in 1902 in the following words. 

 »The period of incubation, varying according to the origin 

 of the disease, causes us to suspect that the essential nature 

 and the manner of development of the mycelium cannot al- 

 ways be the same. They should, on the contrary, depend in 

 some measure upon the origin of rust, a circumstance to 

 which little or no attention at all has hitherto been paid.» 



It should be seen from what has now been stated, that 

 the histological research which Marshall Ward tells 

 us that he has carried out by following step for step 

 the development of secondary pustule flecks which 

 have developed after infection by uredospores, quite 

 as little as what Marshall Ward formerly adduced 

 from his infection-experiments, including the pure 

 cultures, has in no degree refuted, or even touched 

 upon the theory I have advanced and which I am still 

 forced to maintain. 



My intention with these remarks is not to undervalue 

 or depreciate in the least degree the value of the extensive 

 experiments of cultures and infections Marshall Ward has 

 previously described, or of the histological research he has 

 just lately carried out in order to accurately learn the ori- 

 gin of certain secondary pustule flecks. By the former ex- 

 periments he has cast new light upon a very interesting 

 species of grass-rust, viz., the brown rust occuring on the 

 Bromes, and has therel)y effectivel}' contributed to the carry- 

 ing forwards to solution of the rust question as a whole. 

 And his new histological research shows that he is awake 



' J. Eriksson, Einige Bemerhimyen über das Mi/cdium des He.cen- 

 besenrostpilzes der Berberitze. Ber. il. D. Bot. Ges., 1SH7, ]>. 2;5(). 

 - J. Eriksson, Sicr Vorigine etc., T. 15, p. f)? [Extr. ji. ISl]. 



