Tho writ r wishes to otpryus his gratitude to Prof ms cr Lillie 
for his suggestion ef the ori*:ir-aI arotlc*c and f, or unfailir urd 
fcindly advice and instruction ibroufhout the work. 
f tar'ing with th premises as a working hypothesis, that th© 
frse-aurtin sa u ay otic.illy .letera!red f.-?aale firrt, and that 
she wo* Id have h A the normal female mode o* development throughout, 
but for the action of the mal© ho-rene injoctoei into her in uiero 
by «uy of the placental vascular ar^ntemooie, to investigation has 
boon an *tton t to find out the offset of thir calc ho me no on tho 
fer.le ;,ubryo* ic dovolc .rent. This is done by 'tie pii.iv to an- lyoc 
the 5eri©a of natural experiments prei«erteJ, with reference to the 
factors influencing th varying results, and different d,>.rees of 
the oa'se result, proiucad, using tho normals u* control;;. An attest 
has tnereforo been made to test tr.o worfcin/ hypothesis and to answer 
the following quo .-tirns in -addition;- 
(1) 'that are the no ml fersule a- i male soles o~ dcvolopnentV 
{£) fhat chanfc© from the expected normal female ode have 
rosultodt 
te rurlatioafl in the ol b 
effects of the herootj© in the froo-martins st .iicit 
(4) Is tiio action of the hormone limited to any seta of 
structures? If so, to what o re©, ni in what manner, 
does it affoe . each act of crguno? 
Ti.ifi investigation leads to tr.o fellow in general c^nc ion ices 
in addition to producing evidence that tho working hypothesis sac 
4 
so nd;- 
(i) Tho crtsal for»lo development of the yftl orion -uct- 
: , - : ry »©x~ cords U 1 
, 
the develop ©nt of th- female type of ainu© uro *e ii&li a, with 
suburethral -div rticuluc, vestibule, vulva, bu 1 bo •vest; fcu iar laris, 
and clitoris: and the development of a roun Ugu c- t; the de- 
