seems to begin slowly in February. 
In April, specimens with corymbi- 
form shoots and well developed 
trichoblasts are met with, in May 
the trichoblasts have in great 
part attained their definitive size 
and in the two following months 
the growth gradually ceases. As 
the fully developed trichoblasts are 
shed early, hairless specimens may 
be found already in July; in Sep- 
tember such specimens become 
more frequent, and in the following 
months they are almost exclusively 
met with. 
The number of pericentral cells 
varies from 10 to 20, or more fre- 
quently between 12 and 17, but 
the average number is different in 
the different parts of the Danish 
waters as may be seen in the Fig. 395. 
following table showing the numbers Holusiphonia nigrescens: from Seborshoved Grand off Gilleleje: 
€ 4 A, a shoot has developed from the basal joint of the tricho- 
of pericentral cells found in cross last. B, the basal cells of the trichoblasts have produced 
sections of primary axes or prin- pericentral cells but no shoot. C, the two lowermost joints 
£ A ofan unbranched trichoblast have produced pericentral cells; 
cipal long branches below the middle. the second joint a tetrasporangium. 200: 1. 
Number of pericentral cells. 
{| 
Localities over 11 meters’ depth Localities deeper than 11 meters 
Fi | 
average |numbers vary- numberof || average | numbers vary- 
| number of 
number ing between observations | number | ing between | observalions 
North Sea and Skagerak . 15,1 12—18 26 55 a 5,5 
Northern Kattegat ....... 15,3 1120 21 | 12—17 6 
Southern Kattegat ....... 14 I 19 13 HET 2 
Samsø Waters, the Belts 
and Sydfyn Waters... . 14,2 10—19 30 13,3 10—16 12 
Smaaland Sea and Sound. 13,7 12—15 17 
Western Baltic and Baltic 
around Meen.......... ahi 11—16 16 11229) 11—14 5 
Baltic around Bornholm. . 12,1 10—14 9 11 10—13 3 
The table shows that the average number gradually decreases on going 
from the North Sea to Bornholm, and it is also a little smaller in deeper than in 
