.). ERIKSSON, ENTSTEHUNG D. ROSTKRANKH. D. PFLANZEN. 47 



scutes speciaux» (»plasmatische Körperchen») besprochenen 

 Gebilde. Diese Kritik, welche dieselbe ist wie die I ' g Jahre 

 früher gegebene, scheint mir jetzt allzu antiquiert, nachdem 

 meine Stellung zu dieser Frage durch die im voriger Herbste 

 publicierte neue Mitteilung eine wesentlich andere geworden 

 ist. was jedoch Marshall Ward vollkommen ignoriert. 



Sein Kapitel »Eriksson's criticismus» (S. 32) beginnt 

 Marshall Ward mit einem Bedauern darüber, dass ich in 

 meiner kleinen, schon oben citierten Gegenschrift meine frü- 

 here Auffassung aufrecht halte. Ich habe in dieser Schrift 

 folgendes gesagt (S. 142): »The histological researches of 

 Marshall Ward have been carried out with leaves which 

 had been infected with uredospores. After 1, 2, 6 

 and 8 days, preparations have been made of the infected 

 leaf-flecks and. parallel with these, preparations of non-in- 

 fected leaves have also been made», und »I cannot but deeply 

 deplore that Marshall Ward should have drawn such er- 

 roneous conclusions from a research so valuable in itself as I 

 premise this to be». Gleichzeitig hob ich hervor, wie eine 

 histologische Prüfung der Mycoplasmatheorie ausgeführt wer- 

 den muss (S. 144): »This examination must be carried out 

 with parts of plants, which are in the primary sta- 

 dium of disease, where the outbreak of pustules 

 could not be explained as a consequence of ex- 

 ternal infection by means of uredospores or aecidiospores, 

 a stadium which had been described in detail as early as 

 1896 and has been distinguished from the secondary sta- 

 dium which can be wholly explained by the assumption that 

 infection is of external origin. To presuppose an in- 

 ternal germ of disease in a case where infection 

 by uredo- or aecidiospores has already taken place, 

 an infection which gives visible pustules after but 8 to 10 

 days, is unreasonable, just as it is incorrect to wish to 

 apply my way of explaining the origine of a primary pustule 

 fleck to the origine of a secondary one. or, upon the ground 

 of a histological examination of a secondary pustule fleck to 

 base a condemnation of a hypothesis which is applicable to 

 a primary pustule fleck alone. It is. ho Ave v er. this mis- 

 take- of which Marshall Ward now makes himself 

 guilty». Dies ist auch jetzt meine Auffassung. Es wird 



