I M.I \ mi ICEAE 



97 



feels thai the following brief description is war- 

 ranted. 



According to Dangeard and Maupas, tliis para- 

 Bite may occur in great abundance and can be easily 

 cultured in living nematodes lor a long time. The 

 spores are predaceous, retain their vitality for a 

 long time, and up to l"> days they are capable of in- 

 fecting nematodes with which they come in contact. 

 The slender end of the spore apparently is adhe- 

 sive) since it is at this end that it becomes stuck to 



the nematode as the latter brushes against it. In 



spite of the squirming and writhing of the host, the 



spores remain attached in this position and soon 

 germinate. They send a fine, 0.8-0.4 p, germ tube 

 through the cuticle into the nematode (tigs. 5, 6), 



and as the content of the spore passes into its tip it 

 swells into a globular structure. This elongates in a 

 linear direction and becomes filamentous. The young 



thallns is first uninucleate (tig. 9) but very shortly 

 the primary nucleus undergoes division. These divi- 

 sions ire simultaneous, so that a large number of 

 mitotic figures in the same stage may be found in 

 the large sporangia (figs. 12, 13). Dangeard was not 

 certain whether division is direct or indirect, but 

 lik figures indicate that it is mitotic. 



After the thallus has attained its mature length. 

 it divides by transverse walls into two to ten fairly 

 equal segments (fig. 11). These soon separate at the 

 septa, become free, and with further increase in 

 Length and diameter are transformed into either spo- 

 rangia or gametangia. Dangeard' s description and 

 figures suggest that dwarf unicellular thalli may 

 also be formed as in Lagenidium and MysOcytium. 

 The details of cytokinesis and sporogenesis are not 

 well known in spite of Dangeard's description. The 

 incipient sporangia usually possess several small 

 vacuoles which apparently coalesce to form a large 

 central one as they mature (fig. 1.3). and the nuclei 

 lie in the primordial utrical surrounding the vacuole. 

 The spores arc doubtless delimited by progressive 

 cleavage as in other sporangia, and with maturity 

 become clavate and oriented with the thick rounded 

 end directed toward the exit tube (fig. 11). The lat- 

 ter may be straight, curved, or bent at right angles 

 to the surface of the sporangium. As the neck of the 



sporangium perforates the host wall and deliquesces, 

 the spores are all forcibly ejected at one time or in 

 successive groups from the sporangium (fig. 15). 

 In some respects sexual reproduction is similar to 



that of MysOcytium and Lagena. Since conjugation 

 is predominantly lateral (fig. 1(3) Maupas believed 

 that most of the male and female gametangia are 

 segments of different thalli. I leterothallism has not, 

 however, been definitely established. End to end or 

 scalariform conjugation may also occur (fig. 18), 



which suggests that the respective gametangia have 



arisen from the same thallus. The segments which 

 are to become gametangia do not usually increase 

 much in size, and are frequently elongate and cylin- 

 drical. Since the resting spore develops in the larger 

 of the two gametangia and the content of the smaller 

 is mobile, the two have been designated as male and 



female respectively, l'.ach sends out a protuberance 

 toward the other as in some species of SpirOgyra and 

 as these come in contact they fuse at the tips. The 

 content of each ganietangium then usually contracts 

 toward this common canal, and as the intervening 

 wall breaks down the male gamete slowly passes 

 over into the female gametangium and fuses with the 

 ooplasm. No differentiation of an egg cell and peri- 

 plasm has so far been observed, but the contraction 

 of germ plasms toward the conjugation tube seems 

 somewhat similar to that described by Zopf in 

 Lagenidium rabenhorstii. Furthermore, conjugation 

 in Protascus is also similar to sexual reproduction in 

 Lagena, with the exception that in the latter genus 

 the gametangia are usually equal in size and indis 

 tinguishable. and the conjugation tube is formed ex- 

 clusively by the male. 



The zygote soon becomes invested with a thick 

 wall and goes into the resting condition (figs. 17- 

 20). As noted above. Maupas called it a zygospore, 

 while Fitzpatrick referred to it as an oospore. Since 

 reproduction is to a slight degree heterogamous, and 

 the resting spore lies free in the female gametan- 

 gium, the latter's terminology is perhaps more de- 

 scriptive. The writer is nonetheless using the non- 

 eommital term, resting spore, for the time being, 

 since the relationships of Protascus are still ob- 

 scure. No cytologieal study of sexual reproduction 

 from fixed and stained material has yet been made, 

 and it is not known whether the gametes are uni- or 

 multinucleate at the time of fusion. 



The presence of the parasite does not hinder the 

 activities of its host and produce any marked patho- 

 logical effects until after two or three days. By this 

 time, however, the nematode gradually loses its 

 ability to contract and move and becomes slow and 

 heavy. Later as paralysis becomes more marked it 

 undergoes tetanic contractions which last for a long 

 time. In the end a final violent contraction occurs 

 which leaves the animal in a stiff, rigid, twisted posi- 

 tion. In a short while it begins to distend and 

 straighten out as death occurs. 



P. SUBULIFORMIS Dangeard, I.e. 1906. Le Hot. 9: _>.-,<>. 

 Pis, 15-16. 

 /'. auhuKformis vsx. mauposii Maire, 1915. Bull. Sue. 

 Hist. Xat. Afrique Nord. (i: 50. 



Thallus .5-10 ix X 100-100 (u; sporangia 6-7 /x X 

 1(1-1 10 ix, irregular ones up to 26-28 /x in diameter; 

 spores 8-200 in a sporangium, 0.6—3 /x X 20-25 p., 

 apparently adhesive at the slender end; gametangia 

 usually slightly smaller than the sporangia; resting 

 spores 15— 30 ju in diameter, wall 1 -2 fx ; thick. (For 

 further details sec the generic analysis above.) 



Parasitic in nematodes in France (Dangeard. 

 I.e. ) ; Rhabditis trrcs, H. giardi, and R. dolichura in 

 Algiers ( Maupas, '15). 



Maupas' attempts to infect Cosmarium sp., Clot 

 terium lunula, Cladophora sp., and Stigeoclonium 



sp. as well as numerous nematodes including Diplo- 

 gatter ttriatut, I), gracilis, Cephaloleut rigidut and 



