16 



sporangium have been ejected, it suffers transverse rup- 

 ture. The empty sporangium is cast off, and there is 

 left a scar on the side of the " pahsade cell" (PI. III., 

 fig. 18). 



On the same plant we have found longer and narrower 

 "sporangia" (PI. II., fig. 7) with orange-green contents, 

 which we believe to be the young stages of the micro- 

 sporangia described by Berthold. This author gives no 

 figure of these bodies, although he says they are quite 

 similar to those containing the larger green swarm-spores. 

 These gametangia (?) we found in all stages of develop- 

 ment. They possess the same characters as the sporangia, 

 save that they are much longer and narrower. We were, 

 however, unsuccessful in determining the presence of the 

 biciliate orange gametes {?) described by Berthold. This 

 failure on our part, however, may be due to an entirely 

 different cause, which we now suggest. 



Berthold's view that the large, dark green swarm-cells 

 are ova, and the orange swarm-cells sperms, seems 

 scarcely conclusive, not only from the nature of his 

 experiments, but also from Went's assertion that the 

 larger cells can germinate alone. On the whole, the 

 balance of evidence would seem to be in favour of the 

 ordinary "sporangia" being asexual, whilst the "spor- 

 angia" containing the orange micro-spores are, in all 

 probability, "gametangia," forming gametes. Wh}', then, 

 the ditticulty of obtaining cultures from these gametes? 

 We suggest that the plant is becoming apogamous, and 

 that, although the gametangia are formed, and although 

 the gametes are developed in some cases, and may escape 

 from the gametangia, still that they may be sterile. On 

 the other hand, the gametangia may regularly, after 

 reaching a certain stage in development, become vegeta- 

 tive and be transformed into adventitious buds. We have 



