The  Physiology  of  Stock-Breeding. 
79 
oestrus  unless  the  ovaries  be  also  removed.  Further,  unless  the 
extirpation  of  the  ovaries  be  complete,  compensatory  growth 
may  take  place,  and  heat  may  recur  associated  with  the  usual 
outward  indications.  The  same  criticism  may  be  made  about 
the  practice  of  “ webbing,”  which,  according  to  Wallace,^  is 
a method  of  de-sexing  cattle,  prevalent  in  certain  parts  of 
Australia.  In  this  operation  the  oviducts  are  drawn  on  one 
side  so  as  to  destroy  their  normal  anatomical  relation  to  the 
ovaries,  and  prevent  them  from  receiving  the  ripe  ova  that 
are  discharged  at  ovulation.  Such  a method  cannot  inhibit 
the  cyclical  recurrence  of  heat,  since  this  depends  upon  the 
functional  activity  of  the  ovaries  which  are  apparently  left 
intact,  but  webbing  is  no  doubt  a very  efficient  means  of 
preventing  conception.  So  also  with  fowls  ; hens  cannot  be 
properly  de-sexed  or  converted  into  true  “poulardes”  by  merely 
withdrawing  a portion  of  the  oviduct,  although  this  operation 
may  effectively  prevent  the  secretion  of  albumen  which  accom- 
panies egg  laying,  and  so  possibly  be  a factor  in  fattening  and 
general  growth. 
The  influence  of  the  ovaries  upon  the  other  organs  and 
tissues  is  chemical  rather  than  nervous  in  nature.  This  con- 
clusion has  been  established  by  experiments  on  dogs,  rats,  and 
other  animals,  in  which  the  ovaries  were  removed  from  their 
normal  positions  and  transplanted  mid-ventrally  on  to  the  wall 
of  the  body  cavity  or  into  the  tissues  of  the  kidneys.  In  such 
cases  the  ovaries,  although  deprived  of  their  ordinary  nervous 
connections,  still  continue  to  exert  an  influence  upon  the  uterus, 
which  instead  of  undergoing  atrophy,  passes  through  the  usual 
cyclical  changes.^  It  is  supposed,  therefore,  that  the  ovaries 
elaborate  one  or  more  internal  secretions  which  have  a specific 
action  upon  the  uterus,  and  a definite  influence  upon  the  whole 
metabolism.  In  the  same  kind  of  way  evidence  has  been 
adduced  that  the  testes  elaborate  internal  secretions  which 
influence  the  male  metabolism.  It  is  believed  that  these 
ovarian  and  testicular  secretions  circulate  in  the  blood  through- 
out the  entire  body,  their  presence  being  correlated  with  the 
characteristics  of  sex. 
The  functional  relation  between  the  ovaries  and  uterus  is, 
however,  an  especially  close  one.  As  already  stated,  the  uterus 
atrophies  after  ovariotomy.  The  growth  and  congestion  which 
the  uterus  undergoes  during  pro-cestrum  is  synchronous  with 
an  increased  activity  on  the  part  of  the  ovaries,  as  manifested 
by  the  production  of  mature  follicles  at  this  period.  Moreover 
the  more  excessive  hypertrophy  and  vascularisation  which 
' Wallace  : Farm  Live  Stock  of  Great  Britain.  Edinburgh,  1907. 
® Marshall  and  Jolly  : “ On  the  Results  of  the  -Removal  and  Transplantation 
of  Ovaries,”  Tram.  Royal  Soc.,  Fdinburgh,  Vol.  45,  1907. 
