60 BOTANICAL GAZETTE [yory 
The range of the tides at Naples is very much less than at either : 
Beaufort or Bangor, though it cannot be said that tides are wholly ’ 
lacking at this point. The daily readings of the tide gauge near 7 
Naples, furnished by the Italian government, agree closely with 4 
the tides predicted by the U.S. Coast and Geodetic Survey. Extra- 
ordinary conditions of wind and weather, however, may affect the 
range of the tides very appreciably. For the period studied, the — 
maximum daily range of the tides was 2.1 feet, the minimum 0.4, © 
the average 1.0. The water level varied from 0.7 feet below to 1.5 
feet above mean low water of spring tides. The following table 
gives an idea of the relative ranges of the tides at Bangor, Beautort, 
and Naples. 
TABLE I 
Difference in height 
Average range g 
2) 
spri Pp 
tid 
Bansor..5. .. sci 17-0 feet 5-7 feet 
PCAMOLU ee. Say 2.8 0.5 
Naples yc oh. se ro 0.25 
The sexual cells of Dictyota were found to be produced at regular — 
intervals, the time of initiation of the rudiments and liberation of 
the mature gametes bearing a definite relation to the periodic changes 
in the tides. The crops are borne, as at Bangor, at fortnightly q 
intervals. Initiation of the rudiments occurs on the same day aS 
general liberation of the mature gametes, this being two or three 
days after the least neap tide. The number of days required for — 
the development of a single crop is approximately sixteen. The 3 
development of the sori is fairly uniform, not being accelerated at — 
the time of the spring tides. 
A comparison of the facts of periodicity in Dictyota at Bangot, — 
Beaufort, and Naples is given in the following tables. 
between the tidal changes and the fructification of Dictyota. The 
chart should be compared with the charts given by Hoyt (2, PP- 
386, 387) in order to compare the behavior of Dictyota at various 
localities. 
