REVISION OF ENDOGONEAE. 295 



that if these sporangial forms are rightly inchided in the Endogoneae, 

 it seems very probable that the two families should be regarded as very 

 closely related, at least; since they are similar in two other important 

 characters; namely, through the production of specialized zygosporic 

 envelopes, and the presence of highly specialized acrogenous chlamydo- 

 spores. 



As far as I am aware, there has as yet been no successful attempt to 

 germinate the spores of any of these fungi, or to grow them under 

 artificial conditions; and in my own experience I have been unable, 

 after repeated attempts, to induce the zygospores of Endogone pisi- 

 formis Lk. {sphagnophila Atk.) to germinate; or to procure any 

 characteristic growth when uncontaminated spore-masses have been 

 transferred to agar nutrients. The spore-masses of this species, when 

 wintered over out of doors, have also failed to develop further. When 

 placed on fresh sphagnum in a moist chamber for a protracted period 

 during the summer, they usually l>ecome covered by a thin white 

 coating of nondescript hyphae: but although various peculiar Zygo- 

 mycetes, to which reference has been made in a former paper, (Thaxter 

 (1897) p. 12) have at times been observed in such cultures, there is no 

 reason to believe, even though, as in some instances, they seemed to 

 grow from the masses themselves, that the association was other than 

 an accidental one. It seems very probable that the thick-walled 

 spores of the Endogoneae, as in various other instances, germinate 

 as a rule only after special preparation, or under special conditions, 

 and that in Nature they are eaten by various animals; continuing 

 their development after being voided. This is suggested by the fact 

 that I have myself observed uninjured spores of species of Endogone 

 in the stomach-contents of shrews and of myriopods. Until successful 

 cultures have been made, and the development of the three spore 

 types has been successfully followed, or at least until more careful and 

 extended field observations have given some evidence of their actual 

 connection it cannot be assumed that they should all three be included 

 within the limits of a single genus. 



The literature of the Endogoneae, since the type species of the 

 genus Endogone was described by Link in 1809, has been scattered 

 and not very voluminous. With the exception of the paper by Buc- 

 holtz, above mentioned, and the enumerations in the Kryptogamen- 

 flora of Rabenhorst and of Cohn and the Pflanzenfamilien, there has, 

 I think, been no general summary even of this genus. Von Holinel in 

 his Fragmenta, Nos. VI, X and XV, discusses the synonymy and 

 relationships of the genera Endogone, Endogonella, Sclerocystis, 



