318 
NATURE 
[May 20, 1915 

cule of cane-sugar, respectively—both being measured 
when compressed to the osmotic pressure—then 
p(v—bv/V)=RT is found to give a fair fit to the 
results both at 0° C. and at 30° C. 
A closer approximation is obtained with 
(p—a/v?)(v—v/Vb)=RT, 
in which case the same constants give the values of p 
for both 0° C. and 30° C. 
I also find that a Somewhat less good fit is obtained 
from (p+a/v?)(v—vb/V)=RT;; this last equation, how- 
ever, has the advantage that it gives a value of V 
when dp/dV=o, which, assuming that this point is 
the limit of supersaturation, we know is about right; 
that is, V is greater than the molecular volume of 
cane-sugar in the solution, and less than its value 
in a saturated solution, i.e., a solution containing 
about 960 grams per litre at 30° C. 
I would reserve the discussion of the meaning of 
these equations and others, which I have also ob- 
tained, until our final results are published. 
BERKELEY. 

Foxcombe, near Oxford, May 15. 

A Bibliography of Fishes. 
Tue time is ripe—and has, indeed, long been ripe— 
for the publication of a carefully prepared bibliography 
of fishes, to cover the entire range of the subject: 
fishes fossil as well as living, and fishes from many 
points of view, such as anatomy, physiology, 
embryology, pathology, parasitology, distribution, 
taxonomy, everything, in short, excépting matters 
which deal with clerical details of the fisheries. Such 
a compilation, it is clear, means much for this branch 
of zoology, for the literature of the fishes is vast, 
widely scattered, and ill-digested. In fact, I believe 
that there is scarcely an investigator to-day who has 
not been obliged, needlessly, to give weeks or months 
of his time to searching for references. 
The importance of such a bibliography was brought 
home to me about 1890; at that time I began the 
work of collecting references to be used in my studies, 
and as years passed I was able to build up a card- 
catalogue giving author and subject, which proved 
indispensable. Later my catalogue became known to 
correspondents, who in turn found it of use in their 
studies; and they, for their part, were generous in 
contributing references, and thus added notably to its 
value. It next, through the kindness of the Smith- 
sonian Institution, absorbed the bibliography which 
Prof. Goode undertook to publish, and which his 
death left unfinished. Thus the value of the work 
became greater year by year. About 1910 the 
American Museum of Natural History allowed me 
secretarial help in the direction of editing the cata- 
logue for publication. And thereafter, for about a 
year and a half this secretarial work was carefully 
carried on under the supervision of my colleague, Dir 
Louis Hussakof, and since 1914 by Dr. C. R. East- 
man, of the American Museum. 
The scope of the undertaking may be understood 
when one considers that nearly 50,000 references are 
brought together. These have been gathered from 
all sources, notably from all accessible bibliographies, 
serial publications, and bool catalogues. Finally, the 
effort was made to complete the lists of titles by biblio- 
graphies secured in so far as possible from authors 
themselves. To this end circulars were sent out to 
several hundred writers on ichthyology, many of whom 
responded cordially. 
There still remain, however, a number of individual 
writers who have not contributed the titles of their 
publications. I have, accordingly, been led to publish 
the present note in the hope that any who have not 
NO. 2377, VOL. 95| 

already sent to Dr. Eastman or myself their biblio- 
graphies, may be reminded that we are especially 
anxious to make the work as complete as possible. 
We urge that their lists be sent in without delay, for 
the work is undergoing its final revision, and the first 
volume is shortly to go to press. This is the 
““author’s”? volume, which will consist of about 1000 
pages, and include under the names of writers a serial 
list of their publications. The second, or “subject” 
volume, will be a classified index of the titles in 
vol. i. Here one has access to special papers in the 
various branches; for example, in anatomy, distribu- 
tion, embryology. BasHFORD Dean. 
American Museum of Natural History, New York. 

The Use of the Term ‘‘ Pinacoid’’ in Crystallography. 
Can any of your readers help me as to the original 
definition of the familiar term “pinacoid’”’? I suspect 
that it was introduced by C. F.. Naumann about 
1830; it was derived from iraf, a slab, and appears 
from the first to have included two para'lel planes. 
Naumann, for instance (‘‘Anfangsgrtinde der Kry- 
stallographie,”’ 1841, p. 126), uses ‘‘basal pinacoid” 
for the pair of planes parallel to the two lateral crys- 
tallographic axes. But he restricts the use of pina- 
coid to the three possible pairs in a crystal that cut 
only one of the three axes, and (p. 19) defines a 
pinacoid as including ‘‘two parallel planes which are 
parallel either with the base or one of the other co- 
ordinate planes.” 
In 1856 we find Tennant and Mitchell (“* Mineralogy 
and Crystallography”) using pinacoid for a single 
plane of any of these pairs, and this, which is clearly 
a mistake, has been followed by writers of very recent 
date. Story-Maskelyne (‘‘Crystallography,” 1895, 
p. 20) agrees with Naumann, calling the single plane 
a ‘‘pinacoid plane.’’ This latter fact has not been 
observed by the authors of the Oxford Dictionary. 
P. Groth (‘Physikalische Krystallographie”’) in 1876 
and 1885 employed the term in Naumann’s way; but 
in his third edition of 1895 he introduced the term 
““pedion”’ (p. 337) for any single plane, and defined 
a pinacoid (p. 340) as consisting of any two parallel 
planes. 
This extension of the term  pinacoid from 
Naumann’s original usage has_ been adopted 
by Lewis, Liebisch, Miers, and Tutton in their 
authoritative works. The pinacoids parallel to the 
three co-ordinate planes are thus left without a dis- 
tinctive title, and in my own small ‘Outlines of 
Mineralogy” (1913) I have styled them ‘‘ principal 
pinacoids.”’ If the history of the matter is as I have 
traced it, it would seem better if Groth had in- 
vented a new term, side by side with pedion, rather 
than, as was so often done by Rosenbusch in the 
nomenclature of rocks, employed a_ well-established 
term in a new signification. 
GRENVILLE A. J. COLE. 
Royal College of Science for Ireland, 
Dublin, May 1r. f 

A Mistaken Butterfly. 
A FEW summers ago I noticed a fine cabbage butter- 
fly executing a number of gyrations in front of a 
milliner’s shop in New Bond Street, and making 
every effort to get through the plate-glass window. 
Immediately inside the window was a lady’s hat (or 
bonnet, I am not sure of the distinction), ornamented 
by an enormous artificial scarlet poppy. It was quite 
clear that the object of the butterfly’s attention was 
the poppy. Apparently he was guided by sight, and 
not by smell. Epwarp A. Martin. 
Grange Wood Museum, South Norwood, May 12. 



