126 
INA TORE 
[ DECEMBER 10, 1903 
| 
and distribution are added. These, in conjunction | 
with a glossary of terms, render the book available to | 
everyone possessed of an elementary knowledge of | 
botany. In addition to the descriptive text, Mr. Duthie | 
has collected into the notes appended to the species | 
a vast amount of information dealing with the identifi- | 
cation and economic uses of the plants, both in- | 
digenous and cultivated. A perusal of the book not 
only serves to indicate how large a proportion of the | 
Indian plants possess valuable properties, but also can- | 
not fail to impress one with the comprehensive know- | 
ledge which has been acquired by the assiduous work 
of the author and other botanists in India who have 
occupied similar responsible positions. This part in- 
cludes the orders Ranunculacee to Cornaceex; the first 
volume will extend to the Campanulacez, and two 
volumes will complete the work. 
A Laboratory Guide to Qualitative Analysis with the 
Blowpipe. By F. W. Martin, Ph.D. Pp. iv+47. 
(New York: John Wiley and Sons; London: Chap- 
man and Hall, Ltd., 1903.) Price 2s. 10d. 
Tue author regards the restricted employment of the 
blowpipe in analysis as due to the lack of a convenient 
manual or work of reference, which this modest little 
volume of fifty pages is now intended to supply. 
It may be questioned whether, in a well-equipped 
laboratory, the use of the blowpipe as a delicate instru- 
ment for qualitative analysis will supersede other 
methods. For the mineralogist, and especially for 
the mining prospector, the classic of Plattner-Richter, 
which has been translated into English by Cornwall, 
will always hold its place. 
There is nothing in the present volume to call for 
special notice. The matter is very condensed, 
occasionally at the risk of becoming confused. This 
is a description of a coal gas flame :—‘ Its luminosity 
is due to superheated, separated carbon set free from 
acetylene, an easily decomposed gas, which is formed 
from other hydrocarbons composing the gas used as 
fuel by the heat of combustion in the outer envelope.” | 
One is accustomed to the American spelling of | 
“6 luster,’’ ‘“vapor,’’ &c., but the omission of the final | 
e in “ oxid,’’ “ sulfid,’’ ‘‘ chlorid,’’ &c., if intentional 
{oxide also occurs), is un-English. | 
els Ge 
Elementary Experimental Science. Physics. By | 
W. T. Clough. Chemistry. By A. E. Dunstan, | 
B.Sc. Pp. vit+239. (London: Methuen and Co., | 
1904.) Price 2s. 6d. 
Tue course of work provided in this little book is 
intended for young beginners who propose to present 
themselves for examinations of the standard of the 
University Junior Locals. The book aims at supply- 
ing the necessary general information, and also suffi- 
‘ciently explicit instructions for laboratory work. In 
the physics section 157 experiments are provided, and 
in chemistry there are 110, but a number of them are 
more suitable for lecture demonstrations than for 
laboratory exercises. A pupil who works through the 
book, performing the more important of the experi- | 
ments given, cannot fail to obtain a fair knowledge | 
of the fundamental principles of physical and chemical 
science. 
Notes from a Lincolnshire Garden. By A. L. H. A. | 
Pp. 93. (London: Elkin Mathews, 1903.) Price 
2s. 6d. net. 
THESE notes are chatty, interesting, and intelligent. | 
The writer loves the garden and everything that | 
happens in or near it. The book is an instance of the 
humanising effect of nature-study undertaken for the 
love of the subject. The little book may be recom- 
mended to all lovers of country gardens. | 
NO. 1780, VOL. 69] 
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.] 
Heating Effect of the Radium Emanation. 
In a letter to NatuRE of November 5, Prof. Schuster has 
made some remarks on a letter published by us the week 
previously, containing a brief account of some experiments 
to show that the heating effect of radium is temporarily 
reduced by the removal of the emanation, and that the tube 
containing the emanation separated from the radium shows 
a considerable heating effect. 
The difficulty felt by Prof. Schuster apparently arose from 
the fact that we included in the heating effect of the eman- 
ation not only that due to the emanation itself, but also 
that due to the secondary products to which the emanation 
gives rise. It was an oversight on our part to have omitted 
in the sentence ‘‘more than two-thirds of the heating effect 
is not due to the radium at all, but to the radio-active 
emanation which it produces from itself,’’ the words 
‘“ together with the secondary products to which the eman- 
ation gives rise.’’ We were fully aware that the heating 
effect was in part due to the “‘ excited activity ’’ produced by 
the emanation. We specially mentioned the gradual decay 
of the heating effect of radium to a minimum in the course 
of a few hours, and the increase of the heating effect of 
the emanation tube during the same period. These effects 
are connected with the gradual decay and rise, respectively, 
of the excited activity produced by the radium emanation. 
The results would have little meaning if we believed the 
heating effect was due to the emanation alone, for, as Prof. 
Schuster quite correctly points out, the heating effect in 
such a case should at once drop to a minimum after removal 
of the emanation, and the heating effect of the tube con- 
taining the emanation should not at first increase. 
On account of the rapid rise of ihe excited activity in a 
tube containing the radium emanation, the separation of 
the heating effect of the emanation from the complicated 
secondary changes which result from it is a difficult experi- 
niental problem. 
Our letter was merely a preliminary announcement of the 
results of our experiments. It is not possible to discuss the 
| consequences to be deduced from the experiments without 
entering into a detailed description of the measurements. 
We hope to publish shortly a full account of our work on 
the various heating effects. 
McGill University, November 20. 
E. RUTHERFORD. 
H. T. Barnes. 
The Pearl-Oyster Parasite in Ceylon, 
Mr. James Horne t, who is still in Ceylon carrying on 
the investigation of the pearl-oyster fisheries which I started 
in 1902, tells me in a letter just received that he has now 
succeeded in finding the final stage of the cestode larva 
which we found to be the nucleus of the best Ceylon pearls. 
We found this larva (a Tetrarhynchus), in the spring of 
1902, in the pearl-oyster, and, later on, what we took to 
be its later stages in the file-fishes (Balistes) which feed 
upon the pearl-oysters, and we felt pretty certain (as I 
| stated in the first part of my report, now published) that 
| the adult would be found in Trygon or some other large 
Elasmobranch. Mr. Hornell writes from Trincomalie, 
November 16, as follows :—‘‘ Just a line to tell you that I 
have found the final host of Tetrarhynchus unionifactor.* 
“Tt occurs, as surmised, in one of the large rays—a 
| Trygon, I believe, but I have no work on fishes, and cannot 
identify at present. 
“There is, I believe, practically no doubt as to species, 
in the stomach of the ray being two Balistes entire, and 
apparently just devoured, and plenty of bones. In the folds 
1 The name we gave to this Tetrarhynchus larva in our notesand letters 
| until it was ascertained whether the species was known or new.—W. A. H. 
