Masked  Pneumothorax.— This  term  has  been  applied  to  cases  in  which
the  symptoms  of  pneumothorax,  namely,  intense  pleural  pain,  dyspnoea,
pressure  phenomena,  and  displacement  of  the  mediastinal  organs  and
diaphragm,  have  suddenly  occurred  in  the  course  of  advanced  tuberculosis
in  the  absence  of  the  usual  signs  of  pneumothorax  upon  auscultation  and
percussion.  In  the  course  of  some  days  these  signs  gradually  appear,  and
a  circumscribed  pneumothorax  may  be  demonstrated.  They  are  at  first
obscured  by  the  deep  situation  of  the  collection  of  extrapulmonary  air,
which  has  escaped  by  way  of  an  opening  into  the  mediastinum,  an  inter-
lobar space,  or  a  space  between  the  base  of  the  lung  and  the  diaphragm,
and  is  retained  by  previously  formed  pleural  adhesions.  Deep-seated  cir-
cumscribed pneumothorax  is  sometimes  encountered  post  mortem  in  cases
in  which  neither  the  signs  nor  symptoms  have  been  observed  during  life.
THE  DIAGNOSIS  OF  DISEASES  OF  THE  KIDNEYS.
I.  ANATOMICAL  ANOMALIES  OF  THE  KIDNEYS.
The  kidneys  may  be  displaced,  with  or  without  deformity;  the  displace-
ment may  be  congenital  or  acquired.  They  may  vary  in  number:  con-
genital absence  of  one  or  both  kidneys,  supernumerary  kidneys,  atrophy
of  one  kidney.  They  may  be  anomalous  in  form:  general  departures
from  type,  as  lobulation;  hypertrophy  of  one  or  both  organs,  and  fusion
— ^horse-shoe  kidney,  sigmoid  kidney,
disk-shaped  kidney  Finally,  there
may  be  variations  in  the  blood-
vessels,  pelvis,   and   ureters.
