MARCH 14, 1884.] 
are more or less opaque, while the phenomena attend- 
ant upon the glows indicate no such opacity. The 
cosmic-dust theory incurs many of the same objec- 
tions, besides being inherently improbable. In the 
ensuing discussion Prof. E. B. Elliott argued that the 
phenomena were electrical; and Prof. H. M. Paul 
sustained the volcanic-ash theory, pointing out that 
Mr. Hazen’s conclusion as to the simultaneousness 
of the first appearance of the phenomenon at remote 
points depended on a special interpretation of imper- 
fections of the record, depending on cloudiness, and 
claiming the equal privilege of interpreting them in 
another way. 
Ottawa field-naturalists’ club, Canada. 
Feb. 28. — Dr. George M. Dawson read a paper on 
the occurrence of phosphate deposits. After show- 
ing that phosphatic materials were essential to the 
life both of plants and animals, he pointed out that 
the natural cycle of the rotation of these substances 
was interrupted by the action of man, and that large 
quantities of matter which should return to the soil 
were withdrawn from it and taken elsewhere. The 
cropping of the soil impoverishes it, and prevents it 
from yielding as abundantly as formerly, unless the 
loss is compensated by the application of phosphatic 
fertilizers. The grain exported from the port of 
Montreal in a single year has been estimated to con- 
tain 2,574 tons of phosphoric acid, which implies the 
total exhaustion, in as far as phosphates are con- 
cerned, of 75,000 acres of good land, to renew which 
would necessitate the application of some 6,000 tons 
of apatite. It is easily seen that there must always 
be, under the present condition of affairs, an exten- 
sive demand for phosphatic materials; and it becomes 
necessary to inquire where specially concentrated 
natural sources of supply may be found. The occur- 
rence of such deposits was traced from the guano, 
which accumulates in exceptionally dry climates, on 
islands frequented by immense numbers Of sea-birds, 
and such recent deposits as the ‘mussel muds’ of 
Prince Edward Island, through the so-called copro- 
lite beds of England, Carolina, and elsewhere, to 
the more concentrated and metamorphosed deposits 
found in the older rocks of Canada and Norway. 
The main facts in regard to the mode of occurrence 
of apatite deposits in the Laurentian rocks of Canada 
were explained, and the great economic importance 
of such accumulations was considered. Mr. Fraser 
Torrance who, as a mining-engineer, has had large 
experience with the deposits found in the vicinity of 
Ottawa, gave a very interesting description of the 
character of some of the deposits, and of the difficul- 
ties met with in working them, owing to the irregu- 
lar manner of the deposition of the mineral; which 
caunot be considered as occurring either in veins or 
in beds, but as passing from one to the other without 
any regularity of transition. The methods in which 
the present surface-workings are conducted are such 
as to throw most serious difficulties in the way of any 
future mining of the lower deposits. The imperfect 
manner in which apatite has hitherto been manufac- 
tured in Canada was described; and it was stated 
SCIENCE. 
587 
that it was highly probable that much of the mineral 
which was mined in Canada and exported to Great 
Britain returned, either in the raw or manufactured 
condition, to the United States. —— Mr. F. D. Adams 
reported the detection by him, in minerals received 
from Arnprior, of a specimen of rock identical with 
that in which apatite occurs in Norway, and which 
had previously been known only from Norway and 
Finland. 
Boston society of natural history. 
March 5.— Prof. A. Hyatt read a paper on the 
larval theory of the origin of cellular tissue. He 
reviewed the history of investigation among sponges; 
concluding, that, though true metazoa, they possessed 
characteristics which showed them to be derived from 
protozoa. The parallel between the development 
of the cell and egg in the tissue is strictly parallel 
with the evolution of nucleated from unnucleated 
forms in protozoa. Recent investigations have re- 
moved all objections to the homology of the egg or any 
cell with the adult of the nucleated protozoon; and 
the principal mode of reproduction by division is the 
same in all these forms. The egg builds up tissue by 
division after being fertilized by the male or sperma- 
tozoon, just as the protozoon builds up colonies after 
fertilization. Spontaneous division of a cell which 
undergoes encystment takes place, and the sperma- 
tozoa which result from this are true larval monads. 
These resemble the monads derived from division of 
the encysted bodies of protozoa in their forms and in 
their activity. They differ in being able to fertilize 
the female or ovum at once, instead of being obliged 
to grow up to maturity before arriving at this stage. 
Thus all cells may be regarded as larval protozoa, 
and eggs and spermatocysts as encysted larval forms, 
the spermatozoa being equivalent also to larval forms 
which have inherited the tendencies of the mature 
forms in the protozoa at the earliest stages. Thus 
the origin of the tissues in the metazoa is in exact 
accord with the law of concentration and accelera- 
tion in heredity. The cells are larval, which, in 
accordance with this law, have inherited the char- 
acteristics and tendencies of their adult ancestors 
in their earliest stages. The three layers can be 
accounted for as larval characteristics inherited from 
colonies of Infusoria flagellata, which had two forms 
(protective and feeding zoons), and then three (pro- 
tective, feeding, and supporting), these correspond- 
ing to ectoderm, endoderm, and mesoderm. Dr. 
M. E. Wadsworth read a paper on the structure of 
the_earth’s interior, which he held to be a molten or 
semi-fluid mass, which will gradually cool and solidify. 
NOTES AND NEWS. 
THE ‘National academy of sciences will hold its 
next annual session at the National museum, Wash- 
ington, commencing April 15, at eleven A.M. An 
election of five new members will be held. This will 
not make good the vacancies of the past year; for, of 
the ninety-eight members on the roll a year ago, six 
have since died, — Professors Alexander and Guyot 
