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NOTES AND MEMORANDA. 
Angular Aperture of Immersed Object-glasses. — Mr. Wenham 
baying expressed bis willingness to assist in testing tbe aperture of 
Mr. Tolies’ object-glass, wbicb be announced in bis letter to tbe 
Editor, dated 15th July,* would be sent, in order to have tbe result 
verified or not, we have to announce that tbe glass bas not arrived. 
Though Mr. Wenham has declined further discussion directly with 
Mr. Tolies, we think that tbe subject bas not been quite satisfactorily 
determined on tbe question of tbe discrepancies, or perhaps fallacies 
of measurement of extreme angular apertures. If Mr. Wenham bolds 
this opinion, wo hope that be will give us tbe result of bis experience, 
irrespective of any individual question of controversy. 
The British Association. — At tho late meeting tbe amount of 
microscopical work brought before tbe Association was neither large 
nor important. And this we should not have been led to expect from 
tbe fact that tbe President for tbe year was a man who especially 
stands high among English, and we might add Continental natu- 
ralists, as a microscopist and a master of histology. Indeed, with the 
exception of tbe President’s Address, and a few of tbe special addresses, 
there was not much to bo noted. Dr. Carpenter’s opening remarks 
were, as might have been anticipated, a masterly summary of tbe 
present condition of science. And while be left nothing untouched, 
he did not fail to comment on tbe readiness with wbicb men in special 
departments were ready, not only to believe in particular conclusions 
drawn from very recent experiments, but were ever disposed to go 
beyond them, and to give absolute credence to a multitude of other mere 
speculations wbicb took their rise in them. We think tbe President 
touched an important subject in these remarks, and we doubt not that 
tbe tendency will be much lessened for tbe future. We believe tbe 
Address may still be had by communication with tbe Secretaries. 
A Prize for Microscopic Work is offered by tbe Royal Danish 
Society, and we trust some of our Fellows will attempt competition 
for it. It is now a hundred years since tbe celebrated observations 
of Muller on agamous reproduction (gemmiparity) of tbe Naiades 
was published, and although there is no reason to question their 
perfect accuracy on all essential points, it is very desirable to have 
them resumed in tbe actual light of science and with tbe means wbicb 
it possesses to-day. Scbultze, Leuckart, and Minor have furnished 
history with valuable contributions of tbe manner of reproduction of 
tbe Naiades properly called, as Claus and Lankester have of Cbreto- 
gaster ; nevertheless, science ought to be in possession of materials 
sufficient for intelligence on all points of wbicb it is necessary to keep 
account. It is not known definitely what is tbe first origin of buds or 
first individuals, and tbe relations between tbe modes of gemmiparous 
and scissiparous reproduction consequently need to be better explained ; 
complete evolution, from tbe moment when one Naiad leaves tbe egg 
* ‘ M. M. J.,’ page 147, July, 1872. 
VOL. VIII. 
Q 
