SCIENTIFIC SUMMARY. 
199- 
the theory of the swarms of November. Poor M. Schiaparelli ! Happily 
the Astronomische Nachrichten have collected the necessary papers, and he 
will soon he in a position of having his revenge.” 
The Difference of Longitude between Newfoundland and Valencia has re- 
cently been ascertained by means of the Atlantic Telegraph. It has been 
effected by Mr. Gould, who was sent to estimate it by the Coast Survey of 
the United States. A preliminary calculation gave longitude of Heart’s 
Content, Newfoundland, in respect to Valencia, 2h. 51m. 56’5s. Time occu- 
pied by the electricity to pass through the cable, 0-32s. 
BOTANY. 
Distinction of Species among the Algce. — In the last number of the Micro- 
scopical Journal there is an able paper upon this subject by Dr. Braxton 
Hicks. He continues the controversy with Mr. Archer of the Dublin 
Natural History Society. Mr. Archer believes very firmly, that certain 
forms, which he and other botanists have described, are distinct species, fixed 
and immutable. Dr. Hicks doubts this. He contends that, in order to be 
convinced that some of the organisms described by naturalists are undoubted 
species, it would be necessary to have a knowledge of the whole develop- 
ment-history. This knowledge we do not possess, and since certain of the 
temporary conditions of some algae resemble the forms called species there 
appears to be much force in Dr. Hicks’s arguments. In his last paper, Mr. 
Archer advanced several arguments in support of his opinions, and among 
others he adduced the fact of conjugation as the most certain test of the- 
fixity of species. He believes this phenomenon to be the analogue of pollen- 
impregnation, and therefore considers that it shows the maturity of the 
cells in which it occurs. But, in reply, Dr. Hicks asks, looking at the 
process itself, have we any direct evidence u that it is anything more 
than a direct fusion of the contents of two cells ? Whilst admitting 
the value of the analogy, ought we to ascribe more value to the act 
than really appears ? What, for instance, is it in Spirogyra ? A process, 
of one cell joins with the process of another, and their contents thus being 
able to come into contact, fuse into one mass. Before the change began, it 
was impossible to perceive any difference between the two cells. Further 
than this, we often find in some species that, should no second filament be 
near enough, two adjoining cells of the same filament conjugate, by 
throwing out processes round the joint which divides them, and then their 
contents fuse.” Dr. Hicks philosophically contends that, until we have proved 
that no true antheridia exist in Spirogyra, for example, we cannot look upon 
conjugation as anything more than a vegetative process, unconnected with 
the maturity of the cells in which it occurs. 
The Frond-cells of Lemna and Wolffia. — Our readers will remember that 
we, some time since, recorded the discovery of a new British species of 
Duckweed, by Dr. Henry Trimen. This diagnosis was formed upon the 
external characters of the plant. But Professor Gulliver has shown that 
microscopic examination of Lemna minor and Wolffia arrhiza shows 
YOL. VI. — NO. XXIII. Q 
