JUNE 14, 1912] 
it is highly probable that the normal nervous con- 
trol of the digestive functions is exercised pri- 
marily by the local sympathetic mechanism. 
Amphimiais, Variability and Death; Some Facts 
and a Theory: L. B, WauTon, Kenyon College. 
In connection with some studies on the varia- 
bility of zygospores in Spirogyra inflata (Vauch.) 
formed by scalariform (amphimixis) and by lat- 
eral (quasi parthenogenesis) conjugation, certain 
facts are presented which allow an interpretation 
of the cause of death among organisms from a 
different standpoint than the generally accepted 
theory. 
In 200 zygospores produced through the conju- 
gation of cells of different filaments—sexual re- 
production—the coefficient of variation is 9.5093 
for length and 5.7471 for diameter. In the same 
number of zygospores produced by the fusion of 
adjacent cells of the same filament—comparable 
to asexual reproduction—the coefficient of varia- 
tion is 11.9364 for length and 7.5376 for diameter, 
indicating for the given conditions that the cross- 
bred or sexually-produced zygospores, in them- 
selves the young individuals from which the ma- 
ture filaments arise, are relatively 20 per cent. less 
variable in length and 23 per cent. less variable 
in diameter. 
Thus if amphimixis decreases variability, there 
is presented an interesting condition bearing not 
only on the problem of the origin of sex, but also 
on the origin of death, for the theory is equally 
applicable to the individual cell, whether isolated, 
as in the Protista, or associated in colonies, as in 
the higher animals and plants. The development 
of the body in multicellular organisms represents 
merely the development by asexual reproduction of 
an infinite series of cell individuals. Consequently 
the evidence suggests that death occurs as the 
result of the continually forming body cells be- 
coming so variable through the absence of control 
by amphimiais, that eventually some one group 
fails to meet the limits imposed by the environ- 
ment, and these together with the remainder of 
the colony—the individual—perish. 
With a single exception, the available evidence 
is directly in accord with such a theory, although 
in general merely demonstrating that amphimixis 
does not increase variability (Warren, ’99; Castell 
and Phillips, 703; Kellogg, ’06; Wright, Lee and 
Pearson, ’07). The investigations of Jennings, 
711, on Paramecium seem to indicate that here 
conjugation increases variability. The evidence, 
however, was not altogether in harmony, in con- 
SCIENCE 
935 
sequence of which the subject was reserved for a 
future paper based upon additional investigations. 
Even granting that such is the case in Para- 
mecium, where conjugation consists of a tem- 
porary union of gametes (conjugants), it would 
not necessarily follow that a similar condition 
would be found in organisms where a total and 
permanent fusion of gametes (copulants) occurred. 
While it would seem that such a theory as here 
outlined is in advance of the earlier theories as to 
the cause of death which are purely speculative, 
there is need of additional data, and it is hoped 
that the several investigations now in progress 
may throw additional light on the subject. 
On the Autonomic Nervous System of the Rabbit: 
F, W. CARPENTER, University of Illinois. 
The Variation and Ecological Distribution of the 
Shells of the Genus Io: C. C. ADAMS, University 
of Illinois. 
Antero-posterior Dominance in Planaria: C. M. 
Cup, University of Chicago. 
In high concentrations of KCN, alcohol, ether 
and various other agents, which kill the animals 
within a few hours, the resistance of animals and 
pieces varies inversely as their rates of metabolism. 
In low concentrations, to which the animals be- 
come acclimated, the length of life varies directly 
as the rate of metabolism, because the animals or 
pieces with higher rate become more completely 
acclimated. 
By means of these and other experimental 
methods the following conclusions have been 
reached concerning the dynamics of morphogenesis 
in Planaria: the anterior region has the highest 
rate of metabolism, at least during development, 
and from this a gradient in rate extends pos- 
teriorly; each zooid has a similar gradient of its 
own; because it has the highest rate of metabolism, 
the anterior region is dominant, both in morpho- 
genesis and function, over the regions within a 
certain distance limit and in general any level is 
dominant over levels posterior to it and within a 
certain distance limit: the axial gradient in rate 
of reactions is the basis of organic polarity; by 
decreasing or eliminating this gradient hetero- 
morphosis can be induced experimentally: the reac- 
tion-complex which gives rise to a head is the 
fundamental reaction-complex of the specific pro- 
toplasm. 
The formation of a new head in the regulation 
of pieces of Planaria is not a restitution of a 
missing part, but the formation of a new indi- 
vidual head first and the new head region induces 
