9 



i 9 2o] THAXTER— FUNGUS-PARASITES 23 



ruptly compressed, so that above the fourth or fifth cell, as a rule, 

 the series, when viewed edgewise, is thin and flattened, as is shown 

 in fig. 47. The cells appear to be spore mother cells, within which 

 thin-walled, sausage-shaped spores are firmly held by the thickened 

 sheath which surrounds them and is continuous with the wall 

 of the basal cell from which they were originally separated. As 

 far as can be determined from the material available, these spores, 

 which become eventually multinucleate, are separated by the 

 breaking off of the whole or a portion of the series, and are not 

 set free individually, as seems to be the case in the thin-walled 

 species described by Hauptfleisch. What the further history 

 of their development is cannot definitely be stated. , It seems 

 probable that the spore groups are ingested by the xylophagous 

 host, together with other spores of fungi which are present on their 

 natural food, and that, separating as a result of the action of 

 digestive fluids, they either pass through a preliminary period of 

 growth attached to the wall of the digestive tract, or, in being voided 

 with the excrement, become attached and develop at the mouth 

 of the anus. 



Although this species differs in its very thick walls, and in the 

 form and more or less permanent association of its spores in series, 

 its characters seem to correspond in all essential respects with those 

 which are said to distinguish Astreptonema. Fig. 10 of Haupt- 

 fleisch's plate would indicate that his species is characterized 

 by the separation of one or more terminal segments, which precedes 

 the formation of spores. That these may be antheridia, as he 

 suggests, seems quite improbable, and since, as he states, his 

 material was somewhat scanty, it may prove that in this respect 

 as well as in others the two show a very close correspondence. 

 The cytological characteristics seem to be identical. The nuclei 

 in both are large and rather numerous in the primary cell, more so 

 in the denser contents of the distal region, where the spore segments 

 are cut off (fig. 51), there being fewer toward the base, although 

 one seems to be almost always present just above the foot (fig. 49). 

 This foot is entirely similar in both and identical with the corre- 

 sponding organ of Enter obryus; and the spores, although differing 

 in shape and method of association when mature, are produced in a 



