88 



PHYCOMYCETEAE 







outline, and producing numerous zoospores of the same type as those of 

 Monoblepharis. After these have escaped through the apical pore suc- 

 cessive zoosporangia may be formed in the empty sporangial wall by 

 proliferation. Sexual reproduction similar to that of Monoblepharis was 

 reported by Cornu (1871) but has never been found again in either of the 



two species now recognized. (Fig. 26.) 



Monoblepharis, with two species, was 

 first described by the French mycologist 

 Cornu in 1871; since then four or five 

 other species have been recognized. 

 Lagerheim (1900) gave the name Di- 

 blepharis to two species of this genus in 

 which biflagellate swarm cells were ob- 

 served, but in view of the investigations 

 of Cotner referred to earlier, and since 

 the sperm cells in those species were 

 described as uniflagellate, it seems desir- 

 able to consider these as belonging to 

 Monoblepharis. The species of this genus 

 are saprophytic, usually on twigs or 

 other vegetable matter in fresh water. 

 They are attached to the substratum 

 by rhizoids and form unbranched or 

 branched hyphae which are nonseptate 

 except where reproductive organs are 

 formed. The zoosporangia are terminal 

 to the main hypha or its branches, and 

 are mostly more or less cylindrical. After 

 the sporangium is emptied another may 

 be formed within the empty wall by 

 proliferation, or terminally on a sympo- 

 dial branch arising at the base of the 

 old sporangium. The zoospores escape, 

 fully formed, from an opening dissolved 

 in the apex of the sporangium and are typically posteriorly uniflagellate. 

 As mentioned above the frequent biflagellate condition of the zoospores 

 is probably abnormal. 



The oogone in Monoblepharis may be formed terminally or by the 

 enlargement of a subterminal segment. In the former case a second seg- 

 ment immediately below the oogone becomes the antherid; in the 

 latter case the terminal segment becomes the antherid. In M. macrandra 

 (Lagerheim) Woronin the antherids may be terminal on slender 

 branches distant from the oogones. The number of sperms produced in an 



■'-H 



B 



Fig. 27. Monoblepharidales, 

 Family Monoblepharidaceae. Mon- 

 oblepharis insignis Thaxter. (A) 

 Hyphae showing antherids, young 

 oogones and oogones with endo- 

 genous oospore. (B) Oogone ready 

 for fertilization and antherids with 

 sperms. (After Thaxter: Botan. 

 (?a2., 20(10):433-440,Univ.Chicago 

 Press.) 



