a 
-~ 
. 
DECEMBER 4, 1913] 
LETTERS TO THE EDITOR. 
{The Editor does not hold himself responsible for 
opinions expressed by his correspondents. Neither 
can he undertake to return, or to correspond with 
the writers of, rejected manuscripts intended for 
this or any other part of Nature. No notice is 
taken of anonymous communications.] 
Synthesis by Means of Ferments. 
THE short article on the synthesis of glucosides 
by means of ferments in Nature for Novem- 
ber 6 (p. 304) contains the statement, ‘‘hitherto it 
has not been proved that enzymes have anything but 
an analytical action.” ‘‘Prof. Bourquelot . . . has, 
however, obtained results which justify the conclusion 
that the decomposing action continues up to a certain 
point only, and that at this point synthetic action 
begins.”” Prof. Bourquelot’s discovery is by no 
means new, because in 1898 Dr, Croft Hill, in a paper 
on reversible zymolysis in the Transactions of the 
Chemical Society for 1898 (vol. Ixxiii., part 2, p. 634) not 
only showed that the products of fermentation arrested 
the action of the enzyme which caused it, but also 
that if these products reached a certain concentration, 
the enzyme instead of producing further hydrolysis 
began to reverse its action into a synthetic one, and 
built up instead of breaking down. These experiments 
were further extended and described in the Trans- 
actions of the Chemical Society for 1903 (vol. Ixxxiii., 
part 1, p. 578), where he also gives an account of 
experiments made by other authors, and concludes 
(p. 597) with the words: ‘‘These observations, to- 
gether with my own more recent results, make it 
increasingly more probable that the view I put for- 
ward in 1898 is a correct one, namely that all ferment 
actions are reversible.” LauDER BRUNTON. 
to Stratford Place, Cavendish Square. 
Amehocytes in Calcareous Sponges. 
I THINK there can be little doubt that the Amcebz 
referred to by Mr. Orton in Nature of November 27 
are not independent organisms, but constituents of the 
sponge from which he obtained them. I have been 
working for some time past at the problem of the 
origin of the germ cells in the common Grantia com- 
pressa, and have often found the flagellate chambers 
of the sponge crowded with amoeboid cells, which 
can sometimes be seen actually squeezing themselves 
through the layer of collared cells. According to my 
observations, these amcebocytes are immature germ 
cells—oogonia and spermatogonia—and they can often 
be seen undergoing mitosis in the chambers. 
similar phenomena has been described in Sycon by 
Jérgensen. Possibly the ameeboid cells squeezed out 
from the gastral cavity of Sycon by Mr. Orton were 
either of the same nature or else metamorphosed 
collared cells. The latter are very readily detached 
from their proper position in the sponge, and may 
then put out pseudopodia and come to resemble 
Amecebz, as has long been known. 
As it is likely to be some time before my results 
can be ready for publication, I may take this oppor- 
tunity of mentioning that I find that in Grantia com- 
ipressa the amoeboid germ cells arise in the first 
instance from the metamorphosis of collared cells, 
and not, as is sometimes stated, from primitive 
_ amecebocytes, or archzocytes. 
I spent a fortnight in April, 1912, at the Plymouth 
Laboratory in the investigation of these problems, and 
in collecting and preserving the material necessary 
for continuing the work. I have now an almost com- 
plete series of stages of the oogenesis, the most in- 
teresting feature of which is perhaps the feeding of the 
NO, 2301, VOL. 92] 
NATURE 399 
growing ova by nurse cells, the latter being phago- 
cytes which capture other cells and stuff them into the 
ova. I have also a number of stages of spermato- 
genesis. The sponge (G. compressa) is hermaphrodite, 
and sperm morule are to be found (in April), enclosed 
in cover-cells, wedged in between the collared cells in 
the lining of the flagellate chambers. Haeckel de- 
scribed and figured the sperm morulz in this situation 
in various calcareous sponges so far back as 1872, but 
his results do not seem to have been generally accepted. 
The character of the nucleus, to which Mr. Orton 
refers as a means of distinguishing his supposed 
Amoebe from sponge cells, varies greatly according to 
circumstances, and cannot be regarded as conclusive. 
ARTHUR DENDy. 
University of London, King’s College, 
November 27. 
‘Intra-atomic Charge. 
Tuar the intra-atomic charge of an element is deter- 
mined by its place in the periodic table rather than by 
its atomic weight, as concluded by A. van der Broek 
(Nature, November 27, p. 372), is strongly supported 
by the recent generalisation as to the radio-elements 
and the periodic law. The successive expulsion of one 
a and two B particles in three radio-active changes in 
any order brings the intra-atomic charge of the element 
back to its initial value, and the element back to its 
original place in the table, though its atomic mass is 
reduced by four units. We have recently obtained 
something like a direct proof of van der Broek’s view 
that the intra-atomic charge of the nucleus of an atom 
is not a purely positive charge, as on Rutherford’s 
tentative theory, but is the difference between a posi- 
tive and a smaller negative charge. 
Fajans, in his paper on the periodic law generalisa- 
tion (Physikal. Zeitsch., 1913, vol. xiv., p. 131), 
directed attention to the fact that the changes of 
chemical nature consequent upon the expulsion of 
a and 8B particles are precisely of the same kind as in 
ordinary electrochemical changes of valency. He 
drew from this the conclusion that radio-active changes 
must occur in the same region of atomic structure as 
ordinary chemical changes, rather than with a distinct 
inner region of structure, or ‘‘nucleus,’’ as hitherto 
supposed. In my paper on the same generalisation, 
published immediately after that of Fajans (Chem. 
News, February 28), I laid stress on the absolute 
identity of chemical properties of different elements 
occupying the same place in the periodic table. 
A simple deduction from this view supplied me with 
a means of testing the correctness of Fajans’s con- 
clusion that radio-changes and chemical changes are 
concerned with the same region of atomic structure. 
On my view his conclusion would involve nothing else 
than that, for example, uranium in its tetravalent 
uranous compounds must be chemically identical with 
and non-separable from thorium compounds. For 
uranium X, formed from uranium I by expulsion of 
an a@ particle, is chemically identical with thorium, as 
also is ionium formed in the same way from uranium 
II. Uranium X loses two 6 particles and passes back 
into uranium II, chemically identical with uranium. 
Uranous salts also lose two electrons and pass into 
the more common hexavalent uranyl compounds. If 
these electrons come from the same region of the 
atom uranous salts should be chemically non-separable 
from thorium salts. But they are not. 
There is a strong resemblance in chemical character 
between uranous and thorium salts, and I asked Mr. 
Fleck to examine whether they could be separated 
by chemical methods when mixed, the uranium being 
kept unchanged throughout in the uranous or tetra- 
valent condition. Mr. Fleck will publish the experi- 
