66 
Book  Reviews. 
Am.  Jour.  Pharm. 
January,  1920. 
acid,  and  sodium  hydroxide,  successively  increasing  concentrations 
of  hydrogen  ions  from  neutral  or  approximately  neutral  to  Ph.  3.1- 
2.8  favorably  influence  germination  of  the  spores  of  Aspergillus  niger, 
Penicillium  cyclopium,  Botrytis  cinerea,  Fusarium  sp.,  and  Lenzites 
saepiaria. 
(2)  The  range  of  germination  and  the  magnitude  of  the  germina- 
tion quantities  as  influenced  by  hydrogen  ion  concentration  in  the 
solution  depend  upon  the  organism,  germination  being  obtained  with 
the  following  concentrations,  inclusive:  Aspergillus  niger,  Ph. 
2.8-8.8;  Penicillium  cyclopium,  2.9-10.0+;  Botrytis  cinerea,  2.8- 
7.0;  Fusarium  sp.,  2.8-10.0+ ;  and  Lenzites  saepiaria,  2.8-7.0. 
(3)  It  is  not  until  a  hydrogen  ion  concentration  of  Ph.  2.8  or 
above  is  reached  that  inhibition  of  germination  of  the  forms  studied 
is  noticed. 
(4)  Aspergillus  niger,  Penicillium  cyclopitim,  Botrytis  cinerea 
and  Lenzites  saepiaria  show  a  maximum  of  germination  in  the  me- 
dium employed  at  Ph.  2.8-3.1;  Fusarium  sp.  exhibit  a  secondary 
maximum  at  this  concentration. 
(5)  Fusarium  sp.  give  a  pronounced  maximum  of  germination 
at  Ph.  7.4  and  Penicillium  cyclopium  exhibit  a  minor  secondary 
maximum  at  Ph.  7.0-7.4. 
(6)  For  equal  removes  from  the  neutral  point,  OH  ions  appear 
to  be  relatively  more  toxic  to  the  spores  studied  than  H  ions. 
(7)  With  increase  in  length  of  intervals  of  incubation,  the  rela- 
tions of  germination  to  hydrogen  ion  concentration  remain  prac- 
tically the  same. 
(8)  The  curves  of  germination  for  any  organism  are  practically 
identical,  whether  incubated  at  22°  C,  27°  C,  or  31°  C. 
Hejber  W.  Youngk^n. 
A  Critical  Revision  of  the  Genus  Hucai^yptus.    By  J.  H. 
Maiden,  I.S.O.,  F.R.S.,  F.I.S.    Vol.  IV,  Part  8. 
The  part  of  this  comprehensive  monograph  on  the  Genus  Eucalyp- 
tus that  is  now  before  us  continues  this  work  along  the  lines  of  the 
preceding  parts.  The  same  high-class  illustrations  are  likewisQ 
continued.    It  presents  descriptions  of  the  following  species : 
Eucalyptus  tessellaris  F.v.M;  E.  Spenceriana  Maiden;  E.  Clif- 
toniana  W.  V.  Fitzgerald;  E.  setosa  Schauer;  E.  ferruginea  Schauer; 
