Monthly Microscopical! 
Journal, April 1, 18G9. J 
NOTES AND MEMORANDA. 
253 
engaged in mounting specimens, and who have not much time to spare, 
can be had from Mr, Ladd, of Beak Street, Eegent Street. 
Spores in the Air. — The problem of panspermy can be put to the 
test by all who have got good microscopes. It is only necessary, as 
explained in M. Pennetier's book, noticed in our last number, to 
submit a series of glass- slides, covered with glycerine, to a current of 
air drawn by a force-pump, or by other means caused to impinge on 
the glass. An examination of the slides with powers of from 3^ to ^ 
will then in great measure decide the question. It would be interest- 
ing to contrast the air of dry with that of marshy localities. 
Bacteria in Plants. — It is alleged by certain French observers of 
note, that the pulp of plants, even when fresh, contains bacteria in 
considerable quantities. Will some of our readers investigate this 
matter, and give us the results of their labours. 
The Green-colouring Matter of Trochoeta Snb-viridis. — Dr. Baird 
kindly submitted to us some of the green-colouring matter obtained 
by keeping this leach in spirit. Mindful of Schultze's observations, 
we examined it with the spectroscope, but failed to find anything like 
a "characteristic spectrum." There was considerable absorption of 
the violet and partly of the green, but no band was to be found. We 
shall be glad to know whether any of our readers have obtained 
different results. 
Beep Sea-dredgings. — In a paper read before the Botanical Society 
of Edinburgh, Professor Dickie described his mode of examining a 
number of Foraminifera, from a depth of 2000 fathoms, immediately 
under the Gulf Stream. He tested them with weak acid, and finding 
a large residuum of sarcode, he concluded that they had been* living 
at this depth. 
The New Half-inch Object-glass. — In our last number we referred 
to an excellent glass of this kind, since presented to the Society, and 
manufactured by Mr. Collins. In doing so, we referred to the fact 
that Messrs. Powell and Lealand had been the first to make such 
an objective. It would seem, however, that some of our readers 
gather 3d from the note, that Messrs. Powell and Lealand had given up 
the manufacture of these glasses, and this eminent and much respected 
firm consider that the impression thus created was calculated to do 
them an injury. We, therefore, beg to state that Messrs. Powell and 
Lealand still make such glasses, and it needs no comment of ours to 
assure microscopists that these opticians have never turned out any- 
thing but work of the very highest quality and perfection. 
The Nervous System of the Slug.— Our correspondent, J. Daly, 
should communicate with M. Lacaze-Duthiers. We ourselves [Ed. 
M. M. J.] have described * four pairs of nerves as proceeding from the 
supra-oesophagal ganglion ; but we certainly defer to the opinion of so 
high an authority as the French anatomist. 
" The General Anatomy of Limax maximus"—' Quart. Jour. Micro?. 
Science,' January, 1863. 
