of  Animals  and  Vegetables.  i \ 
The  parts  above  mentioned  (viz.  projecting  parts  and 
extremities)  are  fuch  as  will  admit  of  the  greateft  change 
in  their  degrees  of  heat  and  cold,  without  materially  af- 
fecting the  animal.  I find  that  they  will  raife  or  fink 
the  thermometer,  in  fome  degree,  according  to  the  exter- 
nal heat  or  cold  applied ; although  not  in  a proportional 
degree  to  this  application,  as  would  be  the  cafe  in  inani- 
mate matter.  Nor  are  the  living  parts  cooled  or  heated 
in  the  fame  degrees,  which  appears  from  the  application 
of  the  thermometer  to  the  fkin;  for  the  cuticle  may  be 
confidered  as  a dead  covering,  capable  of  taking  greater 
degrees  of  heat  or  cold,  than  the  living  parts  underneath 
can  do ; and  it  might  be  fufpected,  that  the  whole  of  the 
variation  was  in  the  covering.  To  remove  this  doubt  I 
made  the  following  experiments. 
exp.  i.  I funk  the  ball  of  my  thermometer  under  my 
tongue,  which  lay  perfectly  covered  by  all  the  furround- 
ing parts,  kept  it  there  fome  minutes,  and  found  that  it 
rofe  to  97°;  having  continued  it  fome  time  longer  there, 
I found  it  rofe  no  higher.  I then  took  feveral  pieces  of 
ice,  about  the  fize  of  walnuts,  and  put  them  in  the  fame 
fituation,  allowing  them  to  melt  in  part,  but  not  wholly, 
that  the  application  of  cold  might  be  better  kept  up,  oc- 
cafionally  {pitting  out  the  water  arifing  from  the  folu- 
tion : this  I continued  for  ten  minutes,  and  found,  on 
G 2 intro- 
