THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



VoL.V, No. 10] APRIL, 1910. 



WHOL'E SEBIEi: 



VOL. XV, No. 10 



INVESTIGATIONS REGARDING THE PHLOEM AND 

 FOOD-CONDUCTION IN PLANTS. 



BY FRANK U. G. AGRELIUS. 

 Plates XXXVI-XXXVII. 



nnHIS work is an inquiry into the special devices for the 

 J- lateral transfer of food materials in the phloem of vascu- 

 lar plants; to see whether sieve tubes are always present in 

 the higher plants; and to make some comparative studies of the 

 phloem in stems, petioles and fruitstalks. 



At first material in the winter condition was tried but did 

 not prove satisfactory, on account of the difficulty of identify- 

 ing the sieve tubes in their winter condition. Material was 

 again collected, this time including stems, petioles and fruit- 

 stalks, from the spring and summer growth, where the sieve 

 tubes were functioning. Vines were selected at first, from the 

 supposition that the conducting elements would be better de- 

 veloped and therefore plainer. This material was preserved in 

 two-per-cent formaldehyde. As shrinkage of the protoplasm 

 would really assist in making the cell walls more distinct, but 

 little attempt was made to prevent it in the various processes 

 of preparation. 



The celloidin method of imbedding was tried at first but it 

 did not serve the purpose well. It was rather essential in the 

 hard material first collected, but the paraffin method worked 

 better in most cases. By the celloidin method slides having 

 the required large number of sections upon them were difficult 

 to make. If the celloidin were left in the sections it stained 

 too much like the cellulose walls. If dissolved out the cuttings 

 were liable to cupping or to injury in the region of the cam- 

 bium. These fact? led to the choice of the paraffin method, 



(169) 



