D. Keilin and Gf. H. F. Nuttall 
313 
“I. Genetic Hermaphrodites: 
Primary sex glands of both sexes present; 
II. Primary Somatic Hermaphrodites: 
Sex gland or glands of one sex only, but parts of the secondary 
sexual apparatus, internal or external, of both sexes present; 
III. Secondary Somatic Hermaphrodites: 
Sex gland or glands of one sex only; secondary sexual apparatus 
of one sex only, that corresponds to the sex gland present. 
Secondary sexual characters of both sexes present.../’ 
It is important to note that neither among the “wild" Pediculus or from 
specimens derived from crossing capitis and corporis did we discover a single 
specimen with the $ or $ characters localized on opposite sides of the insect’s 
body. The non-occurrence of forms more or less approaching "halved 
gynandromorphs” is an indication that our hermaphrodites have much in 
common with those obtained by Goldschmidt and Poppelbaum 1 in Lepido- 
ptera, these authors having obtained them by crossing Lymantria dispar Linn, 
with its variety japonica Motsch. 
Fertility of Hermaphrodites. 
Several instances are known wherein hermaphrodites have been observed 
to perform sexual functions, exhibiting a normal instinct in respect to 
copulation besides being fertile. 
Not having had an opportunity as yet of studying the behaviour of the 
living hermaphrodites of Pediculus humanus , we are unable to make a definite 
statement regarding their fertility; nevertheless, in view of our observations, 
it is possible for us to distinguish anatomically three categories of herma¬ 
phrodites in lice: those which appear to be capable of functioning (1) as 
males, (2) as females, and (3) that are incapable of functioning either as 
males or females. Among the hermaphrodites that appear capable of pairing 
can be distinguished sterile and fertile individuals which may serve as males 
or females. Moreover, among the fertile hermaphrodites which function as 
females, individuals occur which through some anatomical defect are incapable 
of expelling the fertilized eggs from their body (see p. 302). It should also 
be noted that hermaphrodites often possess perfectly developed testes con- 
1 Goldschmidt, R. and Poppelbaum, H. v. (1914), “ Erblichkeitsstudien an Schmettcrlingen II. 
(2) Weitere Untersuchungen liber die Vererbung der sekundaren Geschlechtscharaktere und des 
Geschlechtes.” Zeitschr.f. Indukt. Abstam. u. V ererbungslehre, xi. 280-316, pis. i-iii. Poppelbaum, 
H. v. (1914), “Studien an gynandromorphen Schmetterlingsbastarden aus der Kreuzung von 
Lymantria dispar L. mit japonica Motsch. Mit einer Uebersicht iiber Ursachen und Interpretation 
der Gynandromorphie bei Arthropoden iiberhaupt.” Ibid., pp. 317-354, pis. iv-v. Goldschmidt, 
R. (xn. 1916), “Experimental Tntersexualitv and the Sex-problem.” American Naturalist, 
l. 705-718. 
