No. I.] VARIATIONS [IN LIMULUS POLYPHEMUS. 85 
instances novel, and it will probably be admitted that they are 
somewhat conducive to speculation. I shall make them alone 
the basis of the argument which follows. There is an obvious 
advantage in treating the subject in this way, for the chances 
of misconception due to confounding unlike results or condi- 
tions with one another are thereby reduced to a minimum. 
We may assume that the three embryos of triple monsters 
are endowed at the outset with equal potentialities and that it 
is merely a question of time that will bring them all to the 
same condition of degeneration. But one embryo must be 
older than the other two, both of which are of the same age. 
If the age of the embryo, that is the time that has elapsed since 
it became an independent embryo, determines the amount of 
degeneration, then C, which is the most degenerate, ought to 
be the oldest ; and 4 and C, being of the same age, ought to 
show the same degree of degeneration. But as this is not the 
case we must assume that some other factor than the time each 
has had to degenerate determines the degree of degeneration. 
We may also dismiss as possible factors the environment, for as 
we have seen that was the same for all classes, yet, in spite of 
that, defective, exuberant, multiple, and normal embryos were 
produced ; and also that when the conditions of development 
were made excessively abnormal, no abnormal embryos were to 
be found. 
In discussing the phenomena of multiple embryos as well as 
the other variations described, we must bear in mind the follow- 
ing facts, which although apparently contradictory in some 
cases, must nevertheless be made to harmonize and be mutually 
confirmatory before any approach to an explanation is possible. 
These facts are : 
(1) Whatever variations are here considered are probably 
due primarily to structural variations resident in the ovum, and 
not to differences in the environment. 
1 It is obvious that we should find at least as many abnormalities under the 
abnormal condition as under the normal, especially if the primary cause of the 
variation is to be sought in the eggs themselves. The absence of abnormalities 
under the former condition is probably due to the fact that under the prolonged 
drastic treatment to which they were subjected, only the normal healthy ones 
survived. 
