INJURIES INDUCED BY PLANTS 123 



is sound. If a tree is in vigorous growth, the smaller blisters 

 low down on the stem, although they increase in size, will induce 

 death only at an advanced age. 



Blisters on the branches are, in themselves, of less importance. 

 They merely contribute to the danger of the further spread of 

 the disease by means of spores. 



As regards the future cultivation on plains and at moderate 

 elevations of this so essentially valuable tree, the following points 

 may be noted in the light of what has been said. It should only 

 be grown singly that is to say, it should form but a small part 

 of a mixture, and it ought, if possible, to be planted somewhat 

 in advance of the other trees. It should never be planted in 

 pure woods, and should always occupy an open situation. Where 

 diseased woods are present in the immediate neighbourhood, 

 it is better to abandon the idea of cultivating this tree. The 

 greatest caution is to be exercised in procuring young trees 

 from outside sources, and plants showing any signs of disease in 

 the seed or plant beds must at once be removed and burned. 



RHIZINA UNDULATA* FR. THE ROOT-FUNGUS 1 



On the light sandy soils of Germany, France, &c., especially 

 in pine and other coniferous woods, one not unfrequently meets 

 with numerous ascophores oiR.undulata growing on the ground. 

 These bear a considerable resemblance to a morel (Fig. 61). 

 In diameter they vary from two thirds of an inch to two inches. 

 The broad ascophore (Fig. 61, a) is undulating and chestnut 

 brown on the upper surface, diverse in shape, of a velvety lustre, 

 and glutinous in wet weather. The under side (Fig. 61, b\ which is 

 destitute of a stalk, is pale yellow and woolly, and is frequently 

 united to the subterranean mycelium by means of numerous loose 

 mycelial strands (Fig. 62). If a section be made of the ascophore, 

 it will be found that towards the upper surface the hymenium 

 (Fig. 63) is composed of asci, each containing eight spores, amongst 

 which filamentous septate paraphyses, clavate towards the apex, 

 will be made out (Fig. 63, a). Besides these there are present 

 numerous non-septate secreting-tubes (b\ which project a little 

 above the surface of the hymenium. These are filled with a 



1 R. Hartig, Naturwissenschaft : Zeitschrift, August -1892. 



* [This occurs on heaths, &c., in England. ED.] 



