Am/a°iyyifo6arm'}  Studies  in  Plant  Mutation.  311 
Fleitman  and  F.  Gatehouse  Test.  U.S.P.,  Jth  Rev. — Aside  from  ex- 
cluding antimony,  these  tests  offer  no  advantages  whatever  over  the 
Gutzeit  mercuric  chloride  and  Bettendorf's  tests ;  in  fact,  they  pos- 
sess all  the  disadvantages  of  the  old  Gutzeit  silver  test. 
One  of  the  chief  difficulties  encountered  with  the  Fleitman  test 
is  to  secure  a  uniform  evolution  of  hydrogen  gas,  which  is  so  essential 
in  the  complete  conversion  of  the  arsenous  oxide  into  arsine.  The 
Gatehouse  modification  offers  but  little  improvement. 
Both  Hager  (Hager,  Ztschr.  Analyt.  Chemie,  2-82)  and  Clark 
(Clark,  Jour.  Chem.  Soc,  1893,  884)  have  pointed  out  that  this  test 
fails  if  arsenic  be  present  in  the  "  ic  "  state.  Curtman  states  that  a 
scarcely  distinguishable  reaction  takes  place  with  o-oi  milligramme 
of  As2Os. 
For  convenience  we  may  summarize  these  tests  as  follows : 
Berzelius-Marsh  .  .  limit  crooi  mgm.  As2Os 
Gutzeit  Silver   "  o'ooi     "  " 
Gutzeit  Mercuric  Chlorid   "  0*002     "  " 
Bettendorf's    "  o'i 
(To  be  continued.) 
STUDIES  IN  PLANT  MUTATION.1 
By  Henry  B.  Si^adk.  "  * 
It  has  long  been  recognized  that  the  species  of  a  given  family  in 
general  have  the  same  or  similar  chemical  principles,  that  alkaloids 
hinder  the  action  of  enzymes  in  some  cases  and  aid  in  others,  and 
that  the  metabolism  of  plants,  by  which  the  protoplasm  continues 
its  activity,  is  a  question  of  enzymic  activity. 
This  suggests  the  thesis  that  changes  in  form  in  the  plant  are 
due  to  changes  in  the  metabolic  process,  induced  by  the  formation 
of  principles  which  interfere  with  the  normal  process,  the  formation 
of  the  principle  in  turn  resulting  from  the  stimulus  of  a  changed 
1  Professor  Slade,  who  was  connected  with  the  University  of  Arizona,  and 
who  died  in  Tucson,  Arizona,  in  June,  1905,  left  among  his  papers  the  unfin- 
ished article  which  we  publish  at  this  time.  It  was  the  beginning  of  a  very- 
interesting  piece  of  work  which,  if  it  could  have  been  finished,  gave  promise 
of  being  far-reaching  in  its  conclusions. 
Professor  Slade  was  known  to  the  readers  of  this  Journal  through  his  valu- 
able paper  on  "  Some  Alkaloids  of  the  Death  Camas,"  published  about  the  time 
of  his  death. — Editor. 
