526 NATURE 

as the evolution or absorption of heat, then the two 
quantities q and I must vary parallel to each other. 
Strictly speaking, therefore, the heat should begin to 
be absorbed from the lowest temperature in the case of 
heating, though its amount is negligibly small, except 
in the Az range.” 
Mr. Honda also tested the question whether the 
magnetic and thermal changes are really different 
aspects of one and the same transformation taking 
place in the substance. This was done by making 
simultaneous observations of the magnetisation and 
the heat evolutions or absorptions in the critical range. 
Both for iron and nickel it was found that the tem- 
perature of the beginning of the magnetic ‘ trans- 
formation” on cooling, and that of its ending on heat- 
ing, coincide well with the corresponding temperatures 
of heat evolution and absorption respectively. In other 
words, the critical temperature as determined mag- 
netically agrees with that as determined thermally. 
The final section of the paper contains a summary 
of the author’s theory of ferromagnetism, according 
to which the shape of the molecules of a_ ferro- 
magnetic substance is nearly spherical, whereas in a 
paramagnetic substance the molecule has an elongated 
or flattened form. The transformation of a_ferro- 
magnetic to a paramagnetic substance at high tem- 
peratures is explained as a consequence of the gradual 
deformation of the spherical molecules with rise of 
temperature. The paper is one which should certainly 
be studied by those who are interested in the Az 
transformation, not only in pure iron but also in steels. 
Inlo KGdaly (Cs 

RECENT MARINE RESEARCHES. 
HE report of the Danish Biological Station for 
IgI4 contains two papers describing investiga- 
tions which have been carried out at the station with 
a view of determining the importance of the detritus 
derived from the decay of Zostera and other sea-weeds 
as a source of food for the invertebrate bottom fauna 
in Danish waters. The idea was recently put forward 
by Dr. C. G. Joh. Petersen that in these waters this 
organic detritus is of much greater importance than 
the plankton. P. Boysen Jensen, in a paper entitled 
“Studies concerning the Organic Matter of the Sea 
Bottom,” deals with the question from a chemical 
point of view. By determination of the quantity of 
pentosan in proportion to the amount of organic 
matter it was found that Zostera was relatively far 
richer in pentosan compounds than the plankton 
organisms. The organic matter of the sea bottom 
occupied an intermediate position. The author con- 
cludes that in the more sheltered waters the organic 
matter of the sea bottom is almest exclusively derived 
from Zostera, whilst in more open waters plankton 
organisms are possibly of some importance. 
The second paper is by cand. mag. H. Blegvad, on 
food and conditions of nourishment among the com- 
munities of invertebrate animals found on or in the 
sea bottom in Danish waters. The stomach contents 
of a great many animals from different localities have 
been studied, but unfortunately the discussion of the 
observations is somewhat illogical and unbalanced, so 
much so that it is difficult to avoid the fear that a 
certain amount of unconscious bias may even have 
crept into the observations on which the discussion is 
based. The author summarises his conclusions as 
follows :— Detritus forms the principal food of nearly 
all the invertebrate animals of the sea bottom, next 
in order. of importance being plant food from fresh 
benthos plants. The value of the living phytoplankton 
in this connection is absolutely minimal, amounting in 
any case to nothing more than an indirect significance 
through the medium of the plankton copepods.”’ 
NO. 2384, VOL. 95| 

|JuLy 8, 1915 

A distinct advance in the study of the question of 
the determination of the age of fishes by the markings 
on the scales has been made by O. Winge in a paper 
on the value of the rings in the scales of the cod as 
a means of age determination, illustrated by marking 
experiments (Meddelelser fra Kommiussionen for 
Havunderségelser, ser. Fiskeri, Bd. iv., No. 8). The 
work is based chiefly on material obtained from cod 
which were marked and liberated by Dr. Johs. 
Schmidt in the neighbourhood of the Faroes and of 
Iceland. Samples of the scales were taken before the 
cod were liberated, and again on their recapture, and 
the two have been compared. Considerably more than 
half the cod marked were recaptured, some of them 
after an interval of a year or more. A novel and very 
convincing method of recording the results of the 
examination of the scales has been used. The lengths 
of the individual sclerites on a line from the centre to 
the periphery of the scale have been measured, and the 
measurements recorded in the form of curves. These 
curves bring out with great clearness the difference 
between the summer and winter growth. The otoliths 
of the fish have also been studied, and the author 
finds that a very high degree of uniformity exists 
between the growth of the scales and that of the 
otoliths, both exhibiting growth rings by which the 
age of the cod can be determined. 
In a paper entitled ‘‘ The Salinity and Temperature 
of the Irish Channel and the Waters South of Ire- 
land”’ (Fisheries, Ireland, Scientific Investigations, 
1913, vol. iv. [1914]) Mr. Donald J. Matthews gives 
an account of the hydrographical investigations which 
were carried out by the Irish Fisheries Department 
between February, 1903, and May, 1912. The results 
are based chiefly on observations made on quarterly 
cruises, which took place in February, May, August, 
and November, supplemented by temperature records 
and salinities obtained at more frequent intervals 
from lightships. An excellent series of charts and 
sections is given setting forth the mean surface and 
bottom temperatures, and salinities for each of the 
months February, May, August, and November, and 
for the whole year. The saltest water enters the 
Irish area between Land’s End and the Scilly Islands, 
and this current of salt, warm water is derived from 
a current which has already entered the English 
Channel from a south-westerly direction. This salt, 
warm current gives rise to a peculiar cyclonic circula- 
tion in the southern entrance of the Irish Channel, 
which may prove to be of considerable biological im- 
portance. The author considers it possible that a 
layer of high salinity water, traces of which are met 
with off the south-west of Ireland, may be connected 
with the salt intermediate layer which flows out of 
the Mediterranean into the Atlantic, and has previously 
been found far to the northwards of the Straits of 
Gibraltar. A salinity maximum which occurs off the 
south-west of Ireland in May is perhaps due to this 
Mediterranean water. The paper concludes with a discus- 
sion of the annual temperature changes in deep water. 
THE FIFTIETH ANNIVERSARY OF THE 
WORCESTER POLYTECHNIG INSTILURE, 
MASS. 
iS Pe Worcester Polytechnic Institute celebrated the 
fiftieth anniversary of its foundation on June o, 
its charter having been signed on May 9, 1865, by 
John A. Andrew, the war governor of Massachusetts. 
There were present representatives from eighty univer- 
sities and colleges, as well as invited guests eminent 
as statesmen, soldiers, and engineers. The dominant 
note of the occasion was not so much that of rejoicing 
over the half-century of progress or that of greater 
enthusiasm for training in efficiency, but rather that 

