182 PHYCOMYCETEAE 



by the breaking of the filament at the apex or through lateral openings 

 the spores escape. The macrospores are larger and may be uninucleate 

 at first, the septation of the hyphae being often oblique. The nuclei divide 

 until usually there are four nuclei to each macrospore. Their walls also 

 become separate from the hyphal walls and from the septa. Holes are 

 dissolved in the lateral wall near the apex or near the base of the con- 

 taining cell and the macrospores escape. The resting spores are usually 

 formed in the hyphae at about the time the chitinous wall of the posterior 

 portion of the intestine begins to become free at the molting stage of the 

 host. These cells may arise by the union of two naked protoplasts or 

 "gametes" within the segment of the filament, the resulting zygotes 

 becoming thick- walled {Arundinula capitata) or the segments of the 

 hyphae may be binucleate and the two nuclei unite. Then a thick wall is 

 formed around each such zygote. The cross septa of the hypha may dis- 

 appear leaving the numerous resting spores free in the tube. They may 

 escape by a distal opening {Taeniellopsis orchestiae Poisson, 1939). In 

 some genera of the family Taeniellaceae the resting spores possess one 

 nucleus at maturity. In the family Arundinulaceae^ there are two nuclei 

 and in the family Eccrinaceae there are four nuclei in each zygote. The 

 sexual process is merely surmised in most cases. The fourth family, Amoe- 

 bidiaceae contains the single genus Amoebidium. The tube or sac-like 

 hypha may divide by oblique w^alls into 4-16 "endoconidia" (Lichten- 

 stein, 1917) which elongate in the mother hypha, piercing the wall and 

 thus forming a cluster of hyphae. More often the contents of the non- 

 septate hyphae divide into 2-4, rarely 8 pyriform amoebae which escape 

 through the dissolved apex of the hypha and creep and float in the sur- 

 rounding water with the larger end foremost. They soon encyst as spher- 

 ical cells. No flagella are apparent. A third mode of reproduction is the 

 formation inside the hyphae by oblique walls of uninucleate fusiform 

 cells, their formation proceeding distally from the base. They escape by 

 lateral openings in the hyphal wall. After escaping the thin membrane 

 becomes thickened thus forming a sort of resting spore. (Fig. 65.) 



The coenocytic hyphae with cellulose walls would seem to indicate 

 some affinity of the Eccrinales with the Phycomyceteae. The absence of 

 flagella even on the naked amoeboid spores of one genus makes their 

 definite placement out of question without further data. The doubtful 

 or reduced modes of sexual reproduction give little help in determining 

 their relationship. 



Drechsler (194()b) has described a fungus Gonimochaete horridula, 

 which attacks and kills free-living soil nematodes and which has some of 

 the characteristics of the Eccrinales, but which differs in many respects. 



iLeger and Duboscq (1929a) used the name Arundinula (and the family name 

 Arundinulaceae) instead of Arundinella, a preoccupied name. 



