at　length　life　and　the　last　handbreadth　of　the　peau　de　chagrin；
  disappear　with　the　gratification　of　a　last　wish。
  Balzac's　＇104＇　studies　had　led　him　over　a　wide　range　of　thought　and
  speculation；　and　his　shadowing　forth　of　physiological　truth　in　this
  strange　story　may　have　been　intentional。　　At　any　rate；　the　matter
  of　life　is　a　veritable　peau　de　chagrin；　and　for　every　vital　act　it
  is　somewhat　the　smaller。　　All　work　implies　waste；　and　the　work　of
  life　results；　directly　or　indirectly；　in　the　waste　of　protoplasm。
  Every　word　uttered　by　a　speaker　costs　him　some　physical　loss；　and；
  in　the　strictest　sense；　he　burns　that　others　may　have　lightso
  much　eloquence；　so　much　of　his　body　resolved　into　carbonic　acid；
  water；　and　urea。　　It　is　clear　that　this　process　of　expenditure
  cannot　go　on　for　ever。　　But；　happily；　the　protoplasmic　peau　de
  chagrin　differs　from　Balzac's　in　its　capacity　of　being　repaired；
  and　brought　back　to　its　full　size；　after　every　exertion。
  For　example；　this　present　lecture；　whatever　its　intellectual　worth
  to　you；　has　a　certain　physical　value　to　me；　which　is；　conceivably；
  expressible　by　the　number　of　grains　of　protoplasm　and　other　bodily
  substance　wasted　in　maintaining　my　vital　processes　during　its
  delivery。　　My　peau　de　chagrin　will　be　distinctly　smaller　at　the　end
  of　the　discourse　than　it　was　at　the　beginning。　　By　and　by；　I　shall
  probably　have　recourse　to　the　substance　commonly　called　mutton；　for
  the　purpose　of　stretching　it　back　to　its　original　size。　　Now　this
  mutton　was　once　the　living　protoplasm；　more　or　less　modified；　of
  another　animala　sheep。　　As　I　shall　eat　it；　it　is　the　same　matter
  altered；　not　only　by　death；　but　by　exposure　to　sundry　artificial
  operations　in　the　process　of　cooking。
  But　these　changes；　whatever　be　their　extent；　have　not　rendered　it
  incompetent　to　resume　its　old　functions　as　matter　of　life。　　A
  singular　inward　laboratory；　which　I　possess；　will　dissolve　a
  certain　portion　of　the　modified　protoplasm；　the　solution　so　formed
  will　pass　into　my　veins；　and　the　subtle　influences　to　which　it　will
  then　be　subjected　will　convert　the　dead　protoplasm　into　living
  protoplasm；　and　transubstantiate　sheep　into　man。
  Nor　is　this　all。　　If　digestion　were　a　thing　to　be　trifled　with；　I
  might　sup　upon　lobster；　and　the　matter　of　life　of　the　crustacean
  would　undergo　the　same　wonderful　metamorphosis　into　humanity。　　And
  were　I　to　return　to　my　own　place　by　sea；　and　undergo　shipwreck；　the
  crustacean　might；　and　probably　would；　return　the　compliment；　and
  demonstrate　our　common　nature　by　turning　my　protoplasm　into　living
  lobster。　　Or；　if　nothing　better　were　to　be　had；　I　might　supply　my
  wants　with　mere　bread；　and　I　should　find　the　protoplasm　of　the
  wheat…plant　to　be　convertible　into　man；　with　no　more　trouble　than
  that　of　the　sheep；　and　with　far　less；　I　fancy；　than　that　of　the
  lobster。
  Hence　it　appears　to　be　a　matter　of　no　great　moment　what　animal；　or
  what　plant；　I　lay　under　contribution　for　protoplasm；　and　the　fact
  speaks　volumes　for　the　general　identity　of　that　substance　in　all
  living　beings。　　I　share　this　catholicity　of　assimilation　with　other
  animals；　all　of　which；　so　far　as　we　know；　could　thrive　equally　well
  on　the　protoplasm　of　any　of　their　fellows；　or　of　any　plant；　but
  here　the　assimilative　powers　of　the　animal　world　cease。　　A　solution
  of　smelling…salts　in　water；　with　an　infinitesimal　proportion　of
  some　other　saline　matters；　contains　all　the　elementary　bodies　which
  enter　into　the　composition　of　protoplasm；　but；　as　I　need　hardly
  say；　a　hogshead　of　that　fluid　would　not　keep　a　hungry　man　from
  starving；　nor　would　it　save　any　animal　whatever　from　a　like　fate。
  An　animal　cannot　make　protoplasm；　but　must　take　it　ready…made　from
  some　other　animal；　or　some　plantthe　animal's　highest　feat　of
  constructive　chemistry　being　to　convert　dead　protoplasm　into　that
  living　matter　of　life　which　is　appropriate　to　itself。
  Therefore；　in　seeking　for　the　origin　of　protoplasm；　we　must
  eventually　turn　to　the　vegetable　world。　　A　fluid　containing
  carbonic　acid；　water；　and　nitrogenous　salts；　which　offers　such　a
  Barmecide　feast　＇105＇　to　the　animal；　is　a　table　richly　spread　to
  multitudes　of　plants；　and；　with　a　due　supply　of　only　such
  materials；　many　a　plant　will　not　only　maintain　itself　in　vigour；
  but　grow　and　multiply　until　it　has　increased　a　million…fold；　or　a
  million　million…fold；　the　quantity　of　protoplasm　which　it
  originally　possessed；　in　this　way　building　up　the　matter　of　life；
  to　an　indefinite　extent；　from　the　common　matter　of　the　universe。
  Thus；　the　animal　can　only　raise　the　complex　substance　of　dead
  protoplasm　to　the　higher　power；　as　one　may　say；　of　living
  protoplasm；　while　the　plant　can　raise　the　less　complex　substances
  carbonic　acid；　water；　and　nitrogenous　saltsto　the　same　stage　of
  living　protoplasm；　if　not　to　the　same　level。　　But　the　plant　also
  has　its　limitations。　　Some　of　the　fungi；　for　example；　appear　to
  need　higher　compounds　to　start　with；　and　no　known　plant　can　live
  upon　the　uncompounded　elements　of　protoplasm。　　A　plant　supplied
  with　pure　carbon；　hydrogen；　oxygen；　and　nitrogen；　phosphorus；
  sulphur；　and　the　like；　would　as　infallibly　die　as　the　animal　in　his
  bath　of　smelling…salts；　though　it　would　be　surrounded　by　all　the
  constituents　of　protoplasm。　　Nor；　indeed；　need　the　process　of
  simplification　of　vegetable　food　be　carried　so　far　as　this；　in
  order　to　arrive　at　the　limit　of　the　plant's　thaumaturgy。　　Let
  water；　carbonic　acid；　and　all　the　other　needful　constituents　be
  supplied　except　nitrogenous　salts；　and　an　ordinary　plant　will　still
  be　unable　to　manufacture　protoplasm。
  Thus　the　matter　of　life；　so　far　as　we　know　it　（and　we　have　no　right
  to　speculate　on　any　other）；　breaks　up；　in　consequence　of　that
  continual　death　which　is　the　condition　of　its　manifesting　vitality；
  into　carbonic　acid；　water；　and　nitrogenous　compounds；　which
  certainly　possess　no　properties　but　those　of　ordinary　matter。　　And
  out　of　these　same　forms　of　ordinary　matter；　and　from　none　which　are
  simpler；　the　vegetable　world　builds　up　all　the　protoplasm　which
  keeps　the　animal　world　a…going。　　Plants　are　the　accumulators　of　the
  power　which　animals　distribute　and　disperse。
  But　it　will　be　observed；　that　the　existence　of　the　matter　of　life
  depends　on　the　pre…existence　of　certain　compounds；　namely；　carbonic
  acid；　water；　and　certain　nitrogenous　bodies。　　Withdraw　any　one　of
  these　three　from　the　world；　and　all　vital　phaenomena　come　to　an
  end。　　They　are　as　necessary　to　the　protoplasm　of　the　plant；　as　the
  protoplasm　of　the　plant　is　to　that　of　the　animal。　　Carbon；
  hydrogen；　oxygen；　and　nitrogen　are　all　lifeless　bodies。　　Of　these；
  carbon　and　oxygen　unite　in　certain　proportions　and　under　certain
  conditions；　to　give　rise　to　carbonic　acid；　hydrogen　and　oxygen
  produce　water；　nitrogen　and　other　elements　give　rise　to　nitrogenous
  salts。　　These　new　compounds；　like　the　elementary　bodies　of　which
  they　are　composed；　are　lifeless。　　But　when　they　are　brought
  together；　under　certain　conditions；　they　give　rise　to　the　still
  more　complex　body；　protoplasm；　and　this　protoplasm　exhibits　the
  phaenomena　of　life。
  I　see　no　break　in　this　series　of　steps　in　molecular　complication；
  and　I　am　unable　to　understand　why　the　language　which　is　applicable
  to　any　one　term　of　the　series　may　not　be　used　to　any　of　the　others。
  We　think　fit　to　call　different　kinds　of　matter　carbon；　oxygen；
  hydrogen；　and　nitrogen；　and　to　speak　of　the　various　powers　and
  activities　of　these　substances　as　the　properties　of　the　matter　of
  which　they　are　composed。
  When　hydrogen　and　oxygen　are　mixed　in　a　certain　proportion；　and　an
  electric　spark　is　passed　through　them；　they　disappear；　and　a
  quantity　of　water；　equal　in　weight　to　the　sum　of　their　weights；
  appears　in　their　place。　　There　is　not　the　slightest　parity　between
  the　passive　and　active　powers　of　the　water　and　those　of　the　oxygen
  and　hydrogen　which　have　given　rise　to　it。　　At　32　degrees
  Fahrenheit；　and　far　below　that　temperature；　oxygen　and　hydrogen　are
  elastic　gaseous　bodies；　whose　particles　tend　to　rush　away　from　one
  another　with　great　force。　　Water；　at　the　same　temperature；　is　a
  strong　though　brittle　solid　whose　particles　tend　to　cohere　into
  definite　geometrical　shapes；　and　sometimes　build　up　frosty
  imitations　of　the　most　complex　forms　of　vegetable　foliage。
  Nevertheless　we　call　these；　and　many　other　strange　phaenomena；　the
  properties　of　the　water；　and　we　do　not　hesitate　to　believe　that；　in
  some　way　or　another；　they　result　from　the　properties　of　the
  component　elements　of　the　water。　　We　do　not　assume　that　a　something
  called　〃aquosity〃　entered　into　and　took　possession　of　the　oxidated
  hydrogen　as　soon　as　it　was　formed；　and　then　guided　the　aqueous
  particles　to　their　places　in　the　facets　of　the　crystal；　or　amongst
  the　leaflets　of　the　hoar…frost。　　On　the　contrary；　we　live　in　the
  hope　and　in　the　faith　that；　by　the　advance　of　molecular　physics；　we
  shall　by　and　by　be　abl