VARIATIOX IX ECHIXOID PLUTEI 
677 
Series C was weak. C4AI living longest. 
Series D showed 15 per cent normal larvae of the type described 
for series A; 4 per cent showed the uncleft condition of thepre- 
oral region. This variation occurring throughout the series. 
Series E. Six per cent normal larvae (type described for A). 
Three per cent with a short additional skeletal rod in one anal 
arm. 
To sum up, these series of eggs show characteristic line varia- 
tions: 
Experiment 1. .4. Auricularian t3'pe. 
Experiment 2. .4. Divided condition of an anal arm. 
Experiment 3. A. Great number of normal larvae. 
B. Weakness. 
C. Weakness. 
D. Strength. Uncleft condition of pre-oral re- 
gion. 
E. Good percentage of normal larvae. Extra 
skeletal rod in one anal arm. 
These variations, it will be noted, are pecuhar to the eggs and 
make their appearance irrespective of the kind of sperm used. 
The only noticeable influence of the sperm is in lots B4M and C4M, 
where the sperm seemed to confer a greater vitality. 
3. DISCUSSION 
In the field in which these observations lie is the work of Stein- 
bruck ('02) and Vernon ('95, '98 and '00), Vernon's two later 
papers being based upon his development of the subject in his 
first. Vernon has also made use of his observations in his ''Va- 
riation in Animals and Plants." 
His work of 1895 is especially valuable in that he shows the 
effect of environment on what I have termed in this paper ''fluc- 
tuating variations." 
It is evident to the reader that the objective point in Vernon's 
work is not the same as in mine. He has ''sought to establish 
that this variation may be considerably increased by the operation 
