TREE ROOTS : THEIR ACTION AND DEVELOPMENT. 1 9 



root-hairs themselves, sHghtly in the cortex opposite the root- 

 hairs, and in the central cylinder. Sections cut at any point of 

 a growing root will give the Peroxidase reaction at all points 

 in the central cylinder, but to the outside only in the root-hair 

 region, results which confirm those got by the above-mentioned 

 investigators. 



(3) When the test is made, however, on mycorhiza-bearing 

 roots vastly different results are obtained. Tests have been 

 carried out with various species of conifer-bearing mycorhiza, 

 both Ectotrophic and Endotrophic. 



I.— Endotrophic Mycorhiza. 



The first plant examined was the Japanese Umbrella Pine 

 {Sciadopiiys verticillatd). The plants possessed a very strong 

 development of Endotrophic mycorhiza, and were particularly 

 suitable for the purpose of testing, since the roots were thick 

 and fleshy and easily and quickly sectioned. 



In practically every section bearing internal mycelium, if trans- 

 ferred quickly enough to the guaiacum tincture on the slide, a 

 deep blue coloration appeared instantly both in the cortex and 

 in the central cylinder without the addition of peroxide. The 

 exceptions gave the reaction on the addition of hydrogen 

 peroxide. On the other hand, rootlets of the same age 

 approximately, from the same or other plants but devoid of 

 internal mycelium, fail to give a reaction for Peroxidase or 

 Oxidase except in the central cylinder. A bluish coloration 

 ultimately appears due to diffusion from the central cylinder. 



Thuja gigantea which possessed Endotrophic mycorhiza gave 

 similar results, as also did Scots pine. Two plants of Thuja 

 gigantea, one from the field with mycorhiza, the other from a 

 pot in the laboratory without mycorhiza, were chosen for 

 comparison. Fresh rootlets of approximately the same age 

 were taken from each plant. In the case of the Endotrophic 

 mycorhiza-bearing roots, in every case the cortex gave the 

 Peroxidase reaction, whereas the roots from the laboratory 

 plant failed to do so. The central cylinder in both plants 

 contains Peroxidase. It was noticeable that parts of the root- 

 system of the mycorhiza-bearing plant from which the fungus 

 was absent failed to give any blue colour. 



Scots pine, in many instances, shows Endotrophic mycorhiza 



