.->_' Mil Ul'HKKJLOSS \1 I S 



into the receptive prominence. A similar s\ iki psis was noted in several cases. In 

 most instances where free spermatozoids win. present in tin venter of the arche- 

 gonium the egg nucleus presented a curious appearance (plate- i, tigs. 47, 4S). A 

 single large nucleolus was present, but scattered through the nucleus there were 

 sometimes a dozen <»i more of intensely staining rounil bodies, which at hist sight 

 looked like- nucleoli, but on more- careful examination were seen to differ from 

 tin- large- nucleolus in that they appeared less homogeneous and generally showed a 

 central vacuole-like structure. These- granules stain very much like- the- body of 

 the- spermatozoid, and it was thought that possibly they might he- derived from a 

 fragmentation of the bod) of the- spermatozoid that had entered the- nucleus, hut 

 this could not he- satisfactorily demonstrated and the- nature- <>t this phenomenon 

 must remain tor the present uncertain. 



Fertilization in Melminthostachys has not been observed. 



SIGNIFICANCE <>l THE ENDOPHYTE. 



I hat tin presence of the- endophyte is essential to the- existence of the- sapro- 

 phytic gametophyte of tin ( >phioglossaceae is indicated by the- failure- of the germi- 

 nating spores to develop unless they become associated with the fungus. Moreover, 

 the universal occurrence ot a similar endophyte in all humus saprophytes among 

 the seed plants indicates that in all of these chlorophyll-less plants the presence of the 

 fungus is necessary for the existence of the host. Although it has not been directly 

 proved, it is generally assumed that one role of the endophyte is the elaboration of 

 some- of the carbonaceous constituents of the humus. The infrequent communica- 

 tion between the external hyphae and the internal mycelium makes it unlikely that 

 the nutritive products are directly absorbed by the fungus, and it seems much more 

 probable that the rhi/oids of the gametophyte are the direct agents of absorption. 

 How the humus constituents are changed by the action of the fungus so that they 

 are available for the cells of the host is not clear, and it is by no means impossible 

 that some at least of the- necessary carbon may be derived from the- fungus itself, 

 in the digestive process to which it is subjected in the- cells of the host. This seems 

 plausible from the fact that in the green prothallia of certain ferns, where presumably 

 the gametophyte is entirely able to supply its own carbon compounds through 

 photosynthesis, these digestive cells appear to he- wanting; at any rate they were- not 

 observed in a number of forms that I have studied. 



The experiments of r/ernetz (Charlotte Ternetz I), show that certain fungi, 

 including endophytic mycorrhizae, are- able- to assimilate free nitrogen and confirm 

 the assumption of earlier observers that the fungus is useful to the- host in supplying 

 it with nitrogen compounds; but, while this is probably a very important part of 

 its functions, it seems to me- that if is not perhaps the only one, anel that the carbon 

 also is supplied, directly or indirectly, through the agency of the fungus. 



In an extended study of the- endophytic mvcorrhi/a of the- saprophytic orchid, 

 Neottia, W. Magnus (W. Magnus I) has shown that two types of mycelium ex- 

 hibited by the endophyte are of very different nature. I he slender, cylindrical 

 hyphae constitute the- active portion of the fungus, which behaves like a parasite 

 toward the- cc-lls which it invades, destroying the starch and probably other constitu- 

 ents of the- cells, but not attacking the- nucleus. The swollen vesicular mycelium, 

 however, is a degenerating structure and is itself destroyed by the cells of the host, 

 which actually digest these fungus mycelia in much the sarin- way that the cells of 

 the leaf of Drosera digest theii prey. Magnus has very graphically shown that the 

 relation of the- two symbionts is mutually antagonistic, each one acting as a parasite 

 on the other; nevertheless the presence of the fungus is essential to the higher 



