5.  Pleural  Effusion, — This  question  of  diagnosis  is  of  daily  occurrence  at
the  bedside  and  demands  special  consideration  (see  p.  1099).  6.  Menin-
gitis.— Doubts  arise  in  some  cases  of  apex  pneumonia,  especially  in  chil-
dren. A  knowledge  that  the  pulmonary  lesions  are  often  masked  will
remind  the  practitioner  that  in  every  case  in  which  meningeal  symptoms
are  present  the  lungs  and  heart  are  to  be  particularly  examined.  7.  EnUric
Fever. — ^There  are  two  principal  sources  of  error,  ratients  suffering  with
toxic  pneumonia  or  the  asthenic  form  of  the  disease  present  septic  symp-
toms identical  with  those  of  enteric  fever  with  mixed  infection.  Clinically,
in  the  absence  of  a  satisfactory  anamnesis  the  diagnosis  is  often  obscure.
