LEPTOLEGNIA 159 



eggs in a thick niosh itf Injiliac. Petersen identifies this as also the 

 parasite previously reported by Miiller on tlie same host. The latter 

 found ('68) that it almost exterminated the animal from a lake (Bogholm 

 So) in Denmark. 



At the 1909 meeting of the North Carolina Academy of Science 

 (reported in Science 30: 188, August 6, 1909) we referred to our plant 

 as a new species of Leptolegnm, hut we now think it to be nothing else 

 than deBary's form. 



Our obser\ations on the sporangia agree with deBary's except that 

 in old cultures the sporangia may become very complex from the ex- 

 tension of a single sporangium into a number of adjoining branches. 

 In fig. I is shown such a sporangium that was observed before and during 

 the discharge. All the spores emerged from the tip of one of the branches 

 (at a in the figure) and the spores at the tips of the other branches had 

 to travel all the way down these and out at a. 



DeBary does not mention the shape or behavior of the spores, but 

 we found them to exhibit some remarkable peculiarities ('09, p. 263). 

 In nearly all cases they emerge from the sporangium much drawn out, 

 as long, more or less cylindrical rods, with the cilia attached to 

 the center on one side. As soon as they escape, the two ends of 

 the rod begin to fold backward, away from the cilia, and fuse as they 

 go, until by complete fusion they lose their identity and form a pear- 

 shaped spore with the cilia near the tip, and the long axis at right angles 

 to the original rod. By killing the spores during emergence they were 

 caught in all stages of this transformation, as shown in fig. 5, in which 

 a shows several spores that were killed in the sporangium. They become 

 more elongated as they pass out and on emergence have the shape shown 

 in b or c. This peculiar habit is confirmed by Petersen ('10, fig. 2). 

 He also adds that the spores while passing out of the sporangium are 

 linked together by their cilia (see p. 4 for later observations by Mr. 

 Couch). 



Two, three, or even more antheridia to the oogonium were common 

 in our material. In one case five were counted. More than two are not 

 mentioned by deBary. The antheridial branches are generally borne as 

 rather short offshoots from a slender main branch that shows a marked 

 tendency to twine about the larger female branches (figs. 2 and 3), but 

 they may terminate a long branch. They are always of diclinous origin. 



The antheridium is full of protoplasm when it is cut off, and is 

 empty a little later; and the amount of protoplasm contained in it is so 

 large that a discharge into the oogonium seems probable. When the 

 empty antheridium is pulled from the oogonium a distinct circular open- 



