Botany. — "Ringing E.xperinients with variegated branches." 

 By Prof. Th. Wkevehs. (Coniiniinicated by Prof. J. W. 

 Moll.) 



(Communicated at the meeting of September 29, 1923). 



For a long time already' the transport of carbohydrates and 

 proteins in plants has heen considered as a question that seemed 

 fairly set at resl. Of late years, liowever, the problem has again 

 been brought into prominence. 



The well-known ringing experiments, notably the extensive ob- 

 servations made in this Held by J. Hanstein ') had settled the belief 

 that the organic matter- was transported along the elements of the 

 phloem. It was left undecided whether the elements of the cribrai 

 system (sieve-tubes and companion cells) or those of the paren- 

 chymatous phloemsystem (cam bi form cells) play the principal part. 

 Czapek's') experiments favoured the (irst view, however, owing to 

 the diametrically opposite conclusions of Deleano') a decision 

 was impossible at the time. 



The primary and the secondary phloem was generally considered 

 as the passage for the conduction of the organic pi'oducts, which, 

 being formed in the leaves, have to be conveyed to the growing 

 points and the reserve-organs. 



In accordance with Th. Hahtig's*) conception it was, however, 

 generally received that in the early spring, when the woody plants 

 start new shoots, the organic matter finds its way from the reserve- 

 stores to ihe shooting parts through the xylem. This hypothesis was 

 based partly upon the results of Hartig's experiments with ringed 

 plants and partly upon A. Fischer's'"! observations regarding the 

 occurrence of carbohydrates in the wood vessels. Researchers refrained 

 from approaching the question as to how this happens in shooting 

 herbaceous plants. 



Now the above theory has latterly been impugned from various 

 quarters. 



') J. Hanstein, Jahrb f. wiss. Botanik. 1860. 



•i CzAPEK, Jahrb. f. wiss. Botanik, 1897. 



'i N. Delkano, Jahrb. f. wiss. Botanik. 1911. 



*) Th. Haetig, Bot. Ztg., 1858. 



°) A. KiscHER, J.ihrb. f. wiss. Botanik, 1890. 



