Pammel — Aiiatomical Characters of Seeds of Leguminosae. 99 



modification of the cell-wall at this point, since with iodine 

 and sulphuric acid the cell-wall colors blue, whereas the light 

 line colors yellow. Haberlandt (83), who studied the develop- 

 ment of Phaseolus vulgains, accepts the Russow explanation, 

 that the light line is clearer and contains less water than the 

 other parts of the cell, while it colors blue with chlor-iodide 

 of zinc. 



Beck (8) thought the appearance might be due to a 

 chemical alteration, but micro-chemical tests did not reveal 

 its nature, though it has but a slight affinity for water. 

 The light line is more refractive than the rest of the wall and 

 chemical changes have taken place. It has certainly not been 

 demonstrated that there is a difference in the amount of water. 

 It is not cuticularized. When stained with carmine and aniline 

 dyes this portion of the wall does not take the stain as readily 

 as others. 



Junowicz (128) found undoubted evidence of cellulose 

 material. The cell-wall at this point was strongly refractive 

 and had a different molecular structure. It was never 

 chemically changed, i. e,, cuticularized. Fickel (332) w^ho 

 studied Cucumis saliva, speaks of a lignification at this 

 point. Harz (99, 2 : 562) accepted the Russow explanation 

 and adds that it is due entirely to physical changes in 

 the laying down of cell-wall substances; it contains less 

 water. It is significant that in several cases mentioned 

 by him the light line disappeared on the application of 

 nitric acid. Tietz (261) considers it due to a chemical 

 modification. Chalon (39) does not express an opinion. 

 Brandza (26) does not seem 1o have investigated the subject 

 very thoroughly, but gives it as his opinion that a chemical 

 modification has taken place. Wigand and Dennert (471) 

 suggest that it is due to a series of erect fissures, and that the 

 Russow explanation is not correct. Weberbauer (467), who 

 studied the same species of JSTelumbium^ agrees with Wigand 

 and Dennert. 



Wettstein (468) agrees with Russow and Sempolowski that 

 chemical and physical modifications occur. The light line 

 slowly colors blue. The absence of pore-canals in the region 

 of the light line causes it to be more dense, as shown by 



