108 



Professor Johannsen: 

 "Meeting is adjourned until after „Die Sitzung ist bis um 2 Uhr 



luncheon." geschlossen." 



Professor Johannsen 

 opened the meeting and introduced eroffnete die Sitzung und erteilte das 

 the first speaker, Dr. v. D eg en. Wort an Hofrat v. Degen. 



Dr. V. Degen: 



"With regard to the determination of the limits of the damages caused by dodders I must 

 refer again to what I reported on the occasion of the Hamburg Congress*). I then proposed 

 — perhaps in other words — that investigations should be instituted, to determine, where 

 this limit should be fixed in Europe, for a knowledge of this limit will be of highest 

 importance in establishing the dodderlatitude. According to my experience this line should 

 be drawn approximately across Europe from East to West starting perhaps near Samara 

 passing probably through Kiew-Krakau, omitting the Carpathians and the Austrian Alps 

 and turning southwards from Vienna to CarnioHa and from here across North Italy, runs 

 then along the Mediterranean, then it crosses France, avoiding perhaps the Central Plateau, 

 westwards to the Atlantic. South of this line the dodder ripens its seeds, and therefore 

 is to be judged quite differently in the marketed seed, than when found North of this line. 



This limit must be regarded as a more or less broad band or zone within which the 

 dodder can mature its seeds or not, according to the climatic conditions during the different 

 years ofobservation; that is to say, a zone in which the naturalisation of dodder is doubtful. 



But also North of this line there exist certain districts in which the Dodder can 

 inflict damage; these are districts, the more favourable climatic conditions of which are 

 characterized by the occurrence of southern wild plants. 



I again urge the importance of fixing this limit in Eui'ope and believe that in America 

 also there should be made a similar determination, for in America surely Dodder has also 

 a polar limit, which lies further south than the clover-culture. 



I therefore propose that a resolution shall be adopted, according to which the Seed- 

 Testing Stations shall be invited, to include, in their programme the investigation of this 

 line. In this respect the work of those Stations, in the countries through which this line 

 probably passes, would be of special importance. 



I shall perhaps from the part of tEe English meet with the objection, that the most 

 widely spread Dodder (Cuscuta Trifolii) was first known and first described precisely in 

 England by Babiugton, one of the keenest of observers. But if we read the original 

 text of the first description, we find that it treated of an introduction at that time, with 

 seed — if I am not mistaken — from Flanders. 



The Budapest Station has thoroughly investigated several questions relating to the 

 Dodder. Thus an experiment was made to determine the influence of the seeding - depth 

 on the occurrence of the Dodder and on the damage, which this parasite causes in the 

 open field; and an experiment to determine the proportion of the occurrence of Dodder 

 to the number of the sowed Dodder - grains. Both experiments are finished and the results 

 published**). 



Since then we have been occupied with the question as to the manner in which way 

 the Dodder - seeds can be most surely and with the least possible loss removed from the 

 clover or alfalfa - seeds. For this purpose generally sieves are employed. ~ In the case of 

 Cuscuta Trifolii this method is satisfactory, but not so for removing the Dodders of 

 larger seeds introduced into Europe from America in recent years, such as Cuscuta 

 arvensis, C. suaveolens („C. racemosa"). For the removal" of these seeds indeed 

 sieves are also employed, but yet we have no specially constructed sieves at our disposal 



•) Jahresberioht der Ver. f . angew. Bot. IT. 1906 : 298. 

 **) Landwirtsohaftliohe Versiichs - Stationen, LXXTII 1912 p. 67—128. 



