1903.] NATURAL SCIENCES OF PHILADELPHIA. 355 



minous plants, and the inference is that the tubercle-producing bacteria 

 have been instrumental in the production of various nitrogenous 

 compounds derived directly from the nitrogen of the atmosphere. It 

 is customary in the poor sandy soil of northern Germany, near Berlin, 

 to grow a great variety of leguminous plants, prominently the yellow 

 luj^ine. The yellow lupine is plowed under and enriches the sandy soil 

 by the decomposition of the nitrogenous substances present in the 

 roots, stems and leaves. The fact that such plants thrive in such poor 

 sandy soil is explained by the activity of the bacterial symbiont. 

 The writer has observed the beach pea, Lathyrus maritimus, growing 

 on the crest of the sea dunes of the New Jersey coast. That the soil 

 is enriched by the growth of this plant is evidenced by the more luxuri- 

 ant development and darker green color of the marram grass, Ammo- 

 phila arenaria, which grows associated with the beach pea on the dunes. 

 Thus the writer previously argued, taking for granted that Frank's 

 assumption was correct, that mycodomatia have a similar function 

 to the leguminous tubercles. But a more careful study has led him 

 to believe that too much has been taken for granted with reference to 

 the function of mycodomatia. 



The abundance of the mycelia in the mycodomatia surprised him 

 and led him to question the validity of the position taken by some of 

 the earher observers that the mycodomatia act in the same way as 

 the leguminous tubercles. It is probable that Frankia brunchorstii 

 is more in the nature of an endotrophic mycorhiza, to be placed inter- 

 mediate between the ectotrophic mycorhiza found on the Indian pipe 

 Monotropa, the short roots of which resemble closely in external appear- 

 ance mycodomatia, and the typical endotrophic mycorhiza found in 

 Thismia and certain other plants, where a definite relationship is 

 established between the nucleus of the host and the fungous hyphse. 

 No such nuclear control of the growth of the fungus Frankia is 

 observed in the mycodomatia of Myrica cerifera. The action of the 

 mycelium of Frankia is much more severe, and in fact its growth sug- 

 gests a true antagonistic symbiosis, for the host cells finally suffer the 

 loss of their protoplasmic contents and collapse, leaving the fungus 

 in possession of the older portions of the mycodomatia. Whether 

 the waxberry derives any benefit from the association of Frankia 

 with its roots can be determined only b}^ careful physiologic 

 experimentation. However, if we have here a true instance of para- 

 sitism, the struggle between host and fungus is long drawn out, 

 and no material damage is done to the host as long as the fungus con- 

 fines its attack to the secondary roots of the waxberry. If this view 



