324 
Hermaphroditism etc. in Pediculus 
from ‘'wild” pediculi or such as were raised by us in the laboratory, and 
(b) that obtained by crossing capitis and corporis. In “wild 55 pediculi the 
few lots which comprised hermaphrodites contained 0-2 to 8 per cent, of 
hermaphrodites. In the progeny of Bacot’s crosses between capitis and 
corporis, however, some families gave over 20 per cent, of hermaphrodites. 
The appearance of hermaphrodites in crosses between capitis and corporis 
is always accompanied by a great decrease in the proportion of females to 
males. 
Since the hermaphrodites found among “wild” pediculi are morpho¬ 
logically similar to those obtained by crossing capitis and corporis, and both 
of these races of Pediculus humanus have ample opportunities for intermingling 
in nature as we have shown, we conclude that the hermaphrodites occasionally 
encountered among “wild” lice are similarly derived from crosses between 
capitis and corporis. 
II. Other abnormalities. 
Besides abnormalities connected with the genitalia of hermaphrodites, we 
have observed others, unconnected with hermaphroditism, affecting the 
structure of the dorsal bands in males, the posterior abdominal lobes in 
females, the spiracles and pleural plates, besides remarkable cases wherein, 
respectively, legs II and III were fused into an elephantine limb, the 
gonopods were fused in the median line, and the peribuccal hairs were 
extraordinarily hypertrophied. 
III. Capitis may be converted into corporis in respect to its 
morphology. 
When capitis are bred in boxes, they gradually acquire all the morpho¬ 
logical characters of corporis. Capitis and corporis constitute but races of 
Pediculus humanus. 
APPENDIX I. 
Evidence proving that capitis may acquire all the characters of corporis. 
We are indebted to Sikora (ix. 1917, pp. 280, 284) for being the first to 
discover that capitis may acquire the morphological characters of corporis. 
This author raised a strain of capitis, obtained from Warsaw, through 4-5 
generations whilst confined in boxes. She records that the insects were then 
found to have lost all the characters of head-lice; they had attained a large 
size, the females averaging 4'22 mm. in length (minimum 3'96 mm., maximum 
4'72 mm.), their legs being as long as in corporis. 
Whilst Bacot found that capitis, after being reared in boxes in the manner 
he employed for corporis, underwent an adaptation whereby they were more 
easily reared under experimental conditions, he makes no mention in his 
publications that the insects likewise undergo an alteration in their 
morphology. He informs us (in. 1919), however, that he had observed an 
