190 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
The first two tables closely parallel the results of the experiments 
on the rate of development. Here again the emphasis is placed on 
$ 
the actual presence or absence of the body covering rather than on 
its form. The crabs reared in sinistral shells had only a slightly 
larger percentage of varying individuals or variants, and only a little 
higher degree of variability than normally reared larvae. But 
those which had never entered a shell showed more than twice the 
normal percentage both of variants and of variability. The crabs 
reared in straight shells were less variable both in respect to the 
number of variants and to the combinations of characters than the 
normal, just as in the earlier experiments nearly ninety percent of 
the “ indifferent ” glaueothoe remained five days in the stage as 
against fifty-seven percent of the normally reared glaueothoe. I 
cannot suggest any explanation for this phenomenon. 
Tables 3 and 4 are somewhat disappointing. The greater varia¬ 
bility of the “sinistral ” and “naked ” crabs over normally reared, is 
not, except with the variations of class A, either united with a 
tendency toward a larger percentage of combinations compared to 
all the combinations for any class, or with leanings toward the 
peculiar variations of class C, although, a priori, both contingencies 
might have been expected. The numerous variant crabs of the 
“ naked ” series were almost all members of class A. Three of the 
most striking variations found, viz .: Ru, R, R, R : Ru, R*, Ru, O, 
Ru, R, R, R : Ru, Ru, R, O and Ru, R, R, R : O, Ru + , Ru, R, 
were presented by crabs from the normal, sinistral and naked series. 
Although the presence of a sinistral shell or the lack of any 
covering for the body affects the larva only with resj^ect 4o one 
series of organs, the pleopods, it might seem that a continuance of 
such a condition might be more potent; at least to conserve the 
variations already present. The rudimentary pleopod on the second 
segment becomes in the female the largest of the abdominal 
appendages. May it not be possible for a similar reconstructive 
power occasionally to reside in those other rudiments which are 
retained by so many sixth-stage larvae, despite the fact that typic¬ 
ally with the males this appendage lacks reconstructive power and 
is lost very early in adolescent life. On experiment, however, it was 
found that outside of the jfieopods no organ was affected at all by a 
continuance of abnormal conditions and only in a sin<de case were 
the latter altered. 
