360 PROCEEDINGS OF THE ACADEMY OF [May, 



apex of the mycoclomatial growths the cortex ceUs are still ahve and 

 by slow growth add to the length of the several branches, forming a 

 mycodomatium. This stage of the fungous development is sometimes 

 found on secondary roots which still show a radial structure with a 

 well-defined endodermis. In such roots the fungus is found especially 

 well marked in the medio- and endocortex and to a limited extent in 

 the exocortex. 



One section showed an appearance suggestive of sporangia as figured 

 in Woronin's paper of 1866, cited above. The writer refers to cer- 

 tain cortex cells which have contents not only reticulate with clear 

 rounded areas enmeshed by the yellowish reticulum, but also suggestive 

 of a lattice-work of protoplasm (PI. XVII, fig. 6a), Hyphae are con- 

 nected not only with the protoplasmic reticulum, but also with the 

 open basket-like protoplasm, so as to suggest that the protoplasmic 

 reticulum owes its origin to the mycelium. A careful study, however, 

 of the relationship of fungus and host cells shows that the reticulum 

 owes its genesis to imbedded starch grains which have been partially 

 dissolved away by the treatment of the sections in mounting, and that 

 hyphse have sent in short branches between the starch grains and hence 

 into the meshes of the protoplasmic reticulum (PI. XVII, fig. 6a). 

 This may have suggested to Woronin the sporangia (zooconidia) 

 which he figures in a grape-like bunch in the cell, each sporangimn 

 (zooconidium) connected by a hypha. Or this reticulate structure 

 may have suggested to Moller^^ a plasmodium of a myxomycete like 

 Plasmodiophora dividing up into a number of spores. 



The writer believes that in suggesting this he has reconciled the 

 earlier opposing views. Woronin is probably right in describing the 

 sporangia (zooconidia) of Frankia, because the mycelium and its man- 

 ner of growth suggests a relationship to the genus Pyihium, and the 

 writer would place, therefore, tentatively, the hyphomycetous genus 

 Frankia among the Oomycetes, close to the genera Pythium and Perono- 

 spora. This view is strengthened if the lattice-like reticulum mentioned 

 above (PI. XVII, fig. 6a) is compared with a figure (fig. 28) given by 

 Tubeuf on p. 139 of his text-book. This figure illustrates the growth 

 of the fungous Phytophthora in the tissues of the leaf of the beech, 

 and the same kind of reticulum is shown. 



In the absence of oogonia and zooconidia, however, in the mycodo- 

 matia of Myrica cerifera, the suggested relationships of the fungus 

 studied by the writer to the Oomycetes cannot be insisted upon. The 



^' MoLLER, "Beitrag zur Kenntniss der Frankia subtilis Brunchorst," Berichte 

 ^er deutschen botanischen Gesellschaft, VIII, 1890, p. 222. 



