to ie ied 
SEXUAL CHARACTERISTICS OF THELIA 611 
acteristics, but the deep-seated changes or underlying causes 
which involve increase of fat stimulate the appearance of the 
secondary sexual characteristics. Just how the Sacculina roots 
or normal ovary bring about the production of changes in the 
blood is not gone into, but certainly the whole differs little from 
the hormone theory which Smith himself opposed vigorously. 
In Smith’s explanation, the Sacculina roots or ovary act upon 
molecules in the blood and the changed blood acts upon the 
somatic tissues. In the hormone theory, the gonad produces 
substances within its own cells, and these substances trans- 
ported by the blood which acts merely as a carrier affect the 
somatic cells to which they are brought. The most questionable 
feature of Smith’s theoretical considerations is the demand of 
the ovary upon the soma, followed by a response on the part of 
the somatic cells. In the arthropods we are wholly without 
evidence that there is any demand coming from the ovary which 
can alter the metabolism of the vegetative cells or stimulate the 
production of certain somatic characteristics. 
Such an individual as that described by Wenke (’06), whose 
work was reviewed in part 2, offers difficulties to a belief in 
ovarian influence exerting an effect upon the developing soma. 
The individual described was a perfect lateral gynandromorph 
with the male somatic characteristics perfectly developed in one 
half, although the only gonad present was one well-developed 
ovary containing eggs almost mature. Such combinations of 
male and female soma are not altogether uncommon in the 
insects and higher crustacea and indicate that in the arthropods 
the genes in the cells producing the somatic structures are not 
influenced either directly or indirectly by the gonads. 
Another line of convincing evidence on the question of the 
independence of somatic tissues in insects is that brought for- 
ward by the works of Steche (12) and Geyer (’13), as previously 
reviewed on pages 536 to 537. These investigators proved that 
the haemolymph of insects was unlike in the two sexes, that 
sometimes color differences were evident in phytophagous species 
and that there were always protein differences demonstrable by 
precipitation tests. Castration failed to alter the characteristic 
JOURNAL OF MORPHOLOGY, VOL. 82, No. 3 
