166 
near the summer maximum. The location of the pulses with respect 
to those of the chlorophyll-bearing organisms (PI. II.) shows in the 
main the same relation that has been observed in other ploiman 
rotifers. In 1895, three angularis pulses lie in the period common 
to both, one of these coinciding in location and two following at the 
next collection. In 1896,two coincide and five follow at the next 
collection or shortly thereafter. In 1897, four follow at an interval 
of a week or a fortnight, and one is located where data are incom- 
plete. In 1898, three coincide and three follow at a short interval, 
and one (June 7), a minor and ill-defined pulse, appears to le on the 
rise of the pulse of the chlorophyll-bearing organisms. In the main 
the dependence of these rotifer pulses upon the recurrent periods of 
increase in these primal links in the food cycle is suggested by this 
coincidence or sequence. The pulses of Brachtonus angularts co- 
incide in the main with those of the totals of ploiman rotifers 
(Vaile): 
There is no vernal pulse in the species at the time of the April— 
May volumetric maximum, and no large autumnal pulse. The pulses 
in August-September, at the close of our period of maximum heat, 
average much greater than those of other months, and still further 
indicate the relation of this species to the higher temperatures. 
The eggs are carried by the female attached to the posterior end 
of the lorica. Usually but a single summer egg is carried at one 
time, but often two, three, and even four, have been seen during the 
height of the period of rapid reproduction. The relation of the 
number of eggs to the pulses is obscured in this species to some 
extent by the fact that the eggs are similar to those of other Brachtio- 
nus and when detached cannot be identified with certainty. Records 
are therefore based upon attached eggs only. The number of these 
depends to some extent on the detachment in the processes of 
collection, killing, and subsequent handling. In a few cases de- 
tached male or winter eggs could be identified with some degree of 
probability by the constitution of the rotiferan plankton. An 
examination of the records of eggs (Table I.) will, however, suffice to 
indicate the prevalence of rapid reproduction during the rise of the 
pulses and the decline in the process during the fall of the pulse. 
Males, male eggs, and winter eggs were recorded in a number of 
instances at the culmination or during the decline of a pulse. For 
example, in 1898, they followed the pulses of August 16, September 

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