547 
Dictyota and Taonia. 
plants of Dictyota . On examining the vessels after a short 
interval, to my astonishment, they were all full of actively 
moving antherozoids. I watched them as long as they re- 
mained active, but found that they came to rest much sooner 
than antherozoids of Fucus would have done. 
Unfortunately I was unable to resume my observations till 
Sept. 1 6. By that time the high spring tides were over and 
the plants had to be dredged up. When examined, the 
plants were found to have liberated all their mature sexual 
elements, but there was a large number of young stages. 
More plants were obtained on the 17th, 18th and the 21st. 
It could be easily seen that the antheridia and oogonia were 
getting more and more mature, but I had to leave the seaside 
without getting plants that were ready for the liberation of 
either male or female elements. Under the circumstances 
it was thought better to wait for another season so as to 
obtain full confirmation before publishing the observation. 
During the present summer several attempts were made to 
secure plants with mature antheridia, but without success until 
Aug. 21. Male plants collected the previous afternoon, and 
kept in the dark all night, were in the morning placed in sea- 
water. There was an immediate liberation of antherozoids 
which were quite as active as those of Fucus. In general 
appearance they seemed at first sight strikingly similar to 
the latter, but a closer examination showed that, both in the 
form of the head and in mode of locomotion, there were 
minute differences which served to distinguish them from the 
latter ; and after fixation and staining, still other and more 
remarkable differences became perceptible. 
Fragments of tetrasporous and oogonial plants were also 
subjected to the same treatment, but at no time could swarming 
organisms be seen in the water in which they had been placed. 
Here it might also be added that, in the later observations 
made on antheridial plants, these actively moving bodies 
were never obtained except from such as had mature antheridia, 
and not even then, unless treated in some such manner as 
above described. Any doubts, however, which might have 
