1100 The American Naturalist. | December, 
“ We summarize the results of the foregoing discussion in the follow- 
ing rules : 
“1. The rule that a name once applied but later becoming invalid 
must not be used again is to be recommended for observance in the 
future; but retroactive force is to be denied to this rule (once a syno- 
nym always a synonym) and alterations of names based upon it are to 
be rejected. 
“2, On the transfer of a species out of the original genus into another 
genus, the original specific name is to be retained. 
“3. The year 1753 is to be retained as the starting point of priority 
for both species and genera. 
“A, In the nomenclature of species the principle of priority is im- 
perative ; only a more certain name must not be replaced by a doubt- 
ul one. 
“5, In the nomenclature of genera a name which has remained un- 
noticed for at least fifty years, cannot later be established in the place 
of one which has become current. 
“6. This rule allows an exception where the name in question, since 
its restoration, has remained in use at least fifty years. 
“ These rules as well as all other proposals proceeding from the 
committee after they have been passed upon by the committee, require 
the approval of a future congress. 
“Tt is much to be desired that botanical nomenclature be placed in 
the closest possible accord with the system of nomenclature now under 
deliberation by the zoologists. 
Fs eee 
“A. ENGLER.” 
“ Vienna, September 21, 1894.” 
(To be continued.) 
VEGETABLE PHYSIOLOGY: 
Macfarlane on Paraheliotropism.—As the result of a series of 
interesting experiments, described in Botanisches Centralblatt, Bd. 61, 
1895, under the title of “ The Sensitive Movements of some Flowering 
Plants under Colored Screens,” Dr. J. M. Macfarlane, of the Univer- 
1 This department is edited by Erwin F. Smith, Department of Agriculture, 
Washington, D. C 
