520 TRANSACTIONS OF SECTION D. 
environment, and, so far as they are concerned, to accept the ‘ hereditary transmission 
of acquired characters.’ The majority of biologists will prefer to conclude that de Vries’ 
“ Fluctuations’ are of two very different kinds, some of them being (a) Germinal 
characters that are hereditary, and subject to Galton’s ‘ Regression’; and others (b) 
Somatic characters that are not hereditary. De Vries uses the term ‘ Mutation’ 
to express (1) a single ‘Saltation’ and (2) the theory that evolution progresses dis 
continuously by means of ‘Saltations.’ He states, however, that his ‘ Mutations’ 
may be small.4 
3. Bateson, Punnett, Shipley and others have erroneously stated in recent years 
that de Vries ‘ pointed out the clear distinction between the impermanent and non- 
transmissible variations which he speaks of as fluctuations, and the permanent and 
transmissible variations which he calls mutations.” 
In this third use of “ Mutation ’—Batesonian, not de Vriesian—the word is applied 
to any and every hereditary character and becomes the same as Weismann’s ‘ Blasto- 
genic Variation.’ ‘ Fluctuation’ similarly in this second use, restricted to (b) as 
explained above, becomes the same as Weismann’s ‘ Somatogenic Variation.’ 
This mistaken reading of de Vries has unfortunately been widely followed, so 
that the Dutch botanist is now generally credited in this country with the bestowal 
of Waagen’s term ‘Mutation’ upon a form of variation previously announced by 
Weismann, instead of upon one (‘ Transilient’) previously announced by Galton. 
The existing hopeless confusion can only be set right by restoring the term ‘ Muta- 
tion ’ to its rightful owner Waagen—a measure of justice for which geologists have been 
contending for several years.® 
For the two other uses of ‘ Mutation’ and for the two kinds of ‘ Fluctuation’ the 
following changes are suggested :— 
For ‘ Mutation’ II. (de Vries), both large and small, substitute Galton’s ‘ Tran- 
silient,’ used as a substantive. The old associations of ‘ Saltation’ are always with 
large variations, and the term should never be applied to small ‘ Transilients.’ The 
term ‘ Magnigrade’ to be used as substantive or adjective, may be conveniently 
applied to a ‘ Saltation’ or ‘ Large Transilient,’ ‘ Parvigrade,’ similarly to a ‘ Small 
Transilient.’ ‘ Magnigrade Evolution’ is ‘ Discontinuous,’ ‘ Parvigrade Evolution ’ 
“ Continuous.’ 
For ‘ Mutation’ III. (Bateson nec de Vries) substitute ‘ Blastogen,’ the sub- 
stantive form of Weismann’s ‘ Blastogenic.’ Other synonyms are ‘ Constitutional,’ 
‘Congenital,’ ‘Genetic,’ ‘Inborn, ‘ Innate,’ ‘Inherent’ and ‘Centrifugal.’ The 
term ‘ Variation ’ has also been used in this restricted sense. 
For ‘ Fluctuation’ I(a) (de Vries) substitute Galton’s ‘ Regressive,’ used as a 
substantive. 
For ‘ Fluctuation’ II. (Bateson) = I(b).(de Vries) substitute ‘Somatogen,’ the 
substantive form of Weismann’s ‘Somatogenic.’ Other terms are ‘ Acquired’ 
(going back to Erasmus Darwin, 1794, and Lamarck, 1809) antithetical to ‘ Inherent,’ 
‘ Centripetal ’ to ‘ Centrifugal,’ and ‘ Modification ’ to ‘ Variation.’ 
The relationships are shown below :— 
II. Non-hereditary characters acquired 
by the body 
I. Hereditary characters originating in the 
germ 
| 
| 
A. Blastogens B. Somatogens 
1. Transilients 2. Regressives 
a Magnigrades 6b Parvigrades. 
4 Tbid., p. 4.—‘* Of course every peculiarity of an organism arises from a previously 
existing one; not however by ordinary variation, but by a sudden though minute 
change,..... The name I propose to give to this ‘* species-forming ” variability is 
Mutability. . . . The changes brought about by it, the Mutations, ... . 
So also on p. 55 :—‘. . . many mutations are smaller than the differences between 
extreme variants ’ [here used as equivalent to ‘ Fluctuations.’] 
° Mendel’s Principles of Heredity, Bateson, Cambridge (1909), p. 287. 
6 F, A. Bather in J. E. Marr’s Presidential Address to the Geological Society of 
London, 1905, Proceedings, pp. Ixxii, Ixxiii. In drawing up the present abstract 
I have received much kind help from my friend, Dr. Bather, 
