126 W. J. ROBBINS. 



being neither attracted nor repelled by light. He believes the 

 meeting of the eggs and spermatozoids is due to chance. 



In brief, Strasburger states that Fucus spermatozoids are 

 negatively phototactic and are chemotactic to the ova. Bordet 

 asserts that they are not phototactic and that there is no che- 

 motaxy. 



MATERIAL AND METHODS. 



The dicecious form, Fucus vesiculosus, was used in the experi- 

 ments. 



To secure spermatozoids or ova for the investigation the 

 methods described by Strasburger (i) were followed. 



Inasmuch as fresh material could not be secured daily, some 

 method of keeping the Fucns in good condition was desired. 

 Sinking the material in the sea was found to yield active sperma- 

 tozoids for only a day or two after bringing it in from its habitat. 

 Fucus plants wrapped in towels wetted with sea water and kept 

 in an ice chest yield active spermatozoids for at least five days 

 after being brought in. The antheridia from fruiting tips kept 

 in sea water in the ice chest for the same length of time were 

 exuded on drying, but the spermatozoids were inactive and lay 

 inert in the antheridia. This difference between the two treat- 

 ments is probably due to differences in oxygen supply. Stras- 

 burger advises shipping fruiting Fucus, desired for active sper- 

 matozoids and living oogonia, in large amounts of sea water, but 

 it appears that wrapping the Fucus in wet cloths and icing it 

 would be preferable. 



EXPERIMENT ON CHEMOTAXY. 



In investigating chemotaxy Pfeffer's capillary tube method 

 was used. The capillary tubes mounted in a drop of sea water 

 containing the spermatozoids were examined under the microscope 

 for about three quarters of an hour for change in direction of 

 motion of the individuals as they passed by the mouth of the 

 capillary tube and for collection of the spermatozoids in the tube 

 as described by Pfeffer and others for various Pteridophytes. 

 The majority of the substances, on account of the strong negative 

 phototaxy of the spermatozoids, were also tested by placing the 

 mounts in the dark and examining them after ten minutes, and 



