i.KPTOMirrs 171 



"These spheroids have been earlier studied by Pringshcim from a 

 morphological ]ioint of view. Their number in each segment is variable, 

 one at least always appears in a young segment; later the number may 

 be increased. Sometimes one may notice them in some place in the body 

 of the segment, sometimes they are localized in the constriction which 

 they obstruct. This last situation is always noticeable when the thread 

 has been broken at the center of the constriction which they obstruct. 

 If the rupture is recent the cellulose granule is simply applied at the 

 opening and obstructs it by simple contact; the protoplasmic contents 

 are thus motionless in the hypha. If the wound is older an adhesion 

 appears between the granules and the cellulose wall, of such a nature 

 that in the same kind of wounds of different ages one can see all the 

 intermediate stages between the application pure and simple of the un- 

 changed cellulose spheroid, which closes the conical tube like a valve, 

 and the adhesion with change of form of this spheroid, which soon forms 

 a new tip of the hypha which may now continue its apical growth. 



"This role of stopcock by immediate application and ultimate ad- 

 hesion is carried out by the cellular granules not only opposite the opening 

 of the apex, produced by accidental ruptures of the filaments, but also 

 opposite all the lateral perforations which one can make intentionally 

 with a needle. 



"As to the manner in which the spheroid fulfills its function, I have 

 been able to observe directly beneath the microscope the rapid move- 

 ment of the cellulose granule as far as the opening intentionally made in 

 the thread. It does not seem to me that this change of position is the 

 result of an intrinsic motion. I consider it rather a mechanical force 

 due to the protoplasmic current which determines the sudden diminu- 

 tion of the turgescence at the moment of the opening of the tube. 



" If the preceding facts seem to me to justify the explanation which 

 I am giving it does not follow, however, that the function of building up 

 the membrane of the hyphae is the only one which can be attributed 

 to the cellulose grains. Perhaps this form of carbohydrate inside of the 

 cell is available for some other use. Whatever it may be, the special 

 function which I have been able to observe is not sufificient to explain 

 the larger number of spheroids in the older segments of the plant." 



The appearance of a culture is more delicate and flaccid than that of 

 a Saprolegnia, the threads about 8.5-161^ in thickness, and the growth is 

 less vigorous and certain under laboratory conditions. We have found 

 slightly boiled cow peas the best medium on which to cultivate it. 

 The sparse branching is all done near the tips and soon presents a 

 dichotomous appearance. The sporangia are sparingly formed from 

 slightly enlarged segments, at first apical then often in rows, opening 



