SCIENTIFIC SUMMARY. 
99 
It had absorbed the •waters -which flowed in the interstices of the schists, 
and had become of a brown colour and coriaceous texture. On exposure to 
the open air it quickly hardened, and was completely transformed into 
brown coal (lignite) with a conchoidal fracture. Its percentage of carbon 
was very similar to that found in the best Saxon lignites. This observation 
shows that the circumstances favourable to the natural carbonisation of 
wood are — (1) Situation among fragments of rocks among which circulate 
freely subterranean waters impregnated with metallic salts. (2) A constant 
and relatively elevated temperature, such as prevails in deep excavations. 
(3) Continuous pressure. 
Chemical Nature of Animal Substances which produce a Cross under ' the 
Polariscope . — In the a Comptes Rendus ” for Nov. 9th appears an interesting 
paper on the above subject by MM. Dastre and Moral. In the yolk of the 
eggs of birds are found spherical corpuscles presenting, when examined under 
the polariscope, a cross whose limbs enlarge as they diverge from the centre. 
M. Dareste, who discovered these bodies in 1866 in the eggs of birds, has 
since found them in other animals — tortoises, osseous fishes, &c., and in 
various parts of the organism. R. Wagner has found them in the vesiculce 
seminales, and M. Balbiani in the adipose body of the silkworm. M. Dareste 
considered them as animal starch, and believed that he had transformed 
them into glucose, making use of this supposed fact as an argument against 
the localisation of the glucogenesis in the liver. The researches of the 
authors prove that these bodies consist of lecithine, a nitrogenous and phos- 
phorised principle made known by Gobley. It is interesting to find a 
nitrogenous matter — considered as amorphous, and of a viscid and colloid 
nature — present a great number of the essential properties of crystals, as- 
suming constantly a regular and symmetrical geometric figure. Lecithine 
is very distinct from starch ; it is not turned blue by iodine ; it dissolves in 
alcohol, and is precipitated by water, whilst the behaviour of starch is quite 
the reverse. The polarisation-cross being, therefore, not peculiar to starch, 
its value in proximate organic analysis is not greater than that of an 
ordinary crystalline form. 
GEOLOGY AND PALAEONTOLOGY. 
Coral Reef s of Hawaii. — A note of some interest appears on this point in 
u Silliman’s American Journal,” for Dec. 1874. It is by Mr. J. D. Dana, 
the well-known coral explorer, and it is as follows : Mr. Darwin, in the 
new edition of his work on Coral Reefs, cites statements from Ellis respect- 
ing the existence of elevated beds of coral detritus 11 round several parts of 
Hawaii, about twenty feet above the level of the sea.” The writer, as Mr. 
Darwin states, saw hardly any reefs about the island, the only point men- 
tioned in my report being the vicinity of Hilo. In reply to an inquiry by 
me on the subject, the Rev. Mr. Coan, long a resident of Hilo, and, as mis- 
sionary, a traveller over various parts of the island of Hawaii, makes the 
• following statement in a letter dated Hilo, October 26th, 1874. Mr. Coan 
is a careful observer of natural objects and phenomena, and has written 
much on the Llawaiian volcanos : i( With respect to your inquiry whether 
H A 
