1 84 THE SAPROLEGNIACEAE 



Olpidiopsis Saprolegniae (Cornu) amend. Fischer. Rabenhorst's Krypt. 

 Fl. 1. part 4: 38, fig. 4. 1892. (2nd. ed.). 

 Olpidiopsis Saprolegniae Cornu, in part. Ann. Sci. Xat. Series 15, 



5: 145. Pl- 3. fig- 10- ^^7^- 



Plate 62, figs. 7-10 



Sporangia usually elliptical but sometimes spherical, smooth, very 

 variable in size, sometimes as much as /Oa through the shortest diam- 

 eter, usually occupying intercalary swellings, but may occur in oogonia 

 or sporangia; emptying by one or more tubes which penetrate the host's 

 wall. Spores very minute and numerous, bean-shaped with two lateral 

 cilia (]\Iaurizio also finds two cilia in 0. major), swimming rapidly, emerg- 

 ing through internal pressure in a slender stream and collecting at the 

 opening in a dense irregular mass. The spores Jerk rapidly and the 

 peripheral ones free themselves by degrees until all get away. _ The 

 whole process occupies several minutes and after the pressure is relieved 

 in the sporangium a good many spores remain in the sporangium and 

 swim rapidly there for a good while, only emerging one by one as they 

 find the opening (apparently by chance). Oogonia up to 74[x thick; al- 

 most always elliptical, the wall rather thick and covered with protu- 

 berances which show remarkable variation from low rounded warts 

 to long, sharp pyramidal spines. Eggs average 330, in diameter, usually 

 one, at times two in an oogonium which they do not quite fill. Anther- 

 idial cells about \S\i. thick, varying little, elliptical to spherical, much 

 smaller than the oogonia, thin-walled, smooth; one, as a rule, attached to 

 each oogonium but rarely as many as three; filled with protoplasm when 

 young, but empty when eggs are mature. 



Found several times around Chapel Hill on A. imperfecta and A. 

 flagellata in Arboretum branch. 



Our plant agrees well with Fischer's description except for the 

 thickness of the antheridia which in Fischer's plant is given as 28-30;!.. 

 In addition to figures by Fischer and Cornu cited above, see Petersen 

 Cio), fig. i8b. 



In one case material with sporangia covered with a glass was watched 

 for half an hour. None of the sporangia emptied while the cover was 

 on. The cover was removed and almost instantly one of the sporangia 

 began shooting out its contents, the spores still in the initial stages of 

 formation. The protoplasm remained at the sporangial mouth and about 

 fifteen minutes after the sporangium had emptied some of the proto- 

 plasm began to assume the form of spores which showed a rocking move- 

 ment. In ten minutes more the entire mass had formed spores, many 

 of which were breaking from the mass and swimming away. The ma- 

 terial was stained with iodine and two lateral cilia demonstrated on the 

 spores. 



In material stained with iodine and then preserved in glycerine 

 which contained a few drops of eosin the sporangia stained a beautiful red, 



