G3G Clu'ford: Tjik Mvcokiiiza of Tim aria unifolia 



threads. In many instances tlic vesicles almost fill the cells 

 They stain a yellowish brown with Bismark brown and alcohoK 

 In the older portions of the root these vesicles are seen to disinte- 

 grate and free their contents in tlie cortex, as has been described 



■m 



by MacDougal in CoralIorJiiza\ 



The nuclei of the cells inhabited by the functus show a varied 

 behavior. In some instances they are double the normal size, very 

 granular, and hyperchromatic. The shape in such instances varies 

 from spherical to oblong ovoid. In roots exann'ned early in May 

 the nuclei of the infected cells were irregular in outline, diminished 

 in si/e, and in some instances had fragmented into two or tlirce 



segments. 



External to the region just described is a second, consisting of 

 two layers of long cylindrical cells, with no intercellular spaces, 

 and thickened at the aniiles. These cells contain active hyphae 



which form more or less dense convolutions at random, but which 

 do 



flu 



appear to influence the nucleus of the cell inhabited, as they 

 are fliirly normal in size and structure. 



The SluiXtli. — The outer layer of the cortex consists of two 

 kinds of cells ; a long cylindrical form, and a short cylindrical 

 form of smaller diameter. The longer cells are placed with their 

 greater axes parallel to that of the root, and they alternate with 

 the shorter ones which have their longest diameter radial. Any 

 row of cells in this layer consists of the two kinds of cells placed 

 alternately, so that each long cell is separated from the end of the 

 one above it by a sliort one. The diameter of the short ones is 

 less than that of the long ones, and as a consequence, the edges 

 of the long ones may be prolonged to meet at the sides of tlie 

 short ones, a fact that may be seen in tangential sections only. 



The outer and inner walls of the smaller cells of this layer are 



f 



noticeably thinner than the later ones and this device allows the 

 ready passage of the hyphae, which crowd through these passage 

 cells so densely as to almost fill the cavities. (PL 372. /. ./.) 



lipideruial Tissue. — External to the sheath is a tissue consisting 

 of four or five layers of thin-walled cells, rich in protoplasm, with 

 no intercellular spaces. This layer is continuous over the apex of 

 the root, on whicii no cap can be distinguished. It is suggested 



I Symbiosis and Sapiophytisni, HulL Ton*. Bot. Club, Oct., 1899. 



