NOTICES OF MEETINGS. 121 


ner to those in most journals. A reply “in our next” will not be 
of much practical use when issued quarterly. 
We wish the publication every success. The record alone of 
the notes from the Society’s note books will be valuable, and we 
hope the Council will not be deterred from publishing if the 
Journal should not turn out a financial success. A special con- 
tribution annually from each member of the Society would enable 
the publication to be carried on. 

TO SECRETARIES OF SOCIETIES. 
In view of the constantly increasing pressure upon our columns, we find it impossible 
to give such full and complete lists of objects shown at the Ordinary Meetings and 
Soirees of Societies, as we hitherto have done. 
We do not wish all lists expunged from reports, but that there should be some 
method in enumeration is evinced by the numerous letters we have received during 
the last six months, to the effect that in the opinion of our correspondents, many of 
these lists are of but little use. Our own views coincide completely with those of 
our correspondents. We had long been of opinion that the lists of objects might be 
cut down with advantage, but wished for twelve months at least, to provide a per- 
manent record, useful to young Societies and to those wishful to exhibit at Soirees. 
We have done this, and therefore ask the Secretaries of Societies to aid us in making 
their lists as interesting as possible, confining it to objects shown to illustrate papers 
es other communications, new apparatus, and to rare specimens met with in the 
istrict. 

NOTICES OF MEETINGS. 
DONCASTER MICROSCOPICAL SOCIETY.—At a meeting in the 
Grammar School, on Wednesday evening, March 8th, Dr. J. Mitchell Wilson 
in the chair, a paper on ‘“‘ Diatoms”’ was read by Mr. J. M. Kirk. Twenty- 
nine members were present. Diatoms, like Desmids, are simple cells, 
having a firm outer coating, within which is enclosed an endochrome. The 
Diatomacez are divided into two chief groups; those which are single 
frustules, and those which cohere in masses. The name seems to have 
been given to them by the readiness with which the latter may be cut or broken 
through ; hence they are sometimes called ‘‘ brittle worts.” During the healthy 
life of a Diatom, the process of self-division is being continually repeated, and 
a very rapid multiplication of frustules thus takes place, all of which are 
repetitions of the same individual form. These original forms are of great 
variety. A large part of the ‘infusorial earths’ deposited at the bottom of 
lakes is composed of Diatoms, one such remarkable deposit being the tripoli or 
rotten stone, used for polishing metals. The well-known Turkey stone, also 
“silicon,” now sold for polishing plate, is similarly composed. Such is the 
abundance of Diatoms in some rivers and estuaries, that their multiplication is 
affirmed by Ehrenberg to have exercised an important influence in blocking up 
harbours and diminishing the depth of channels. It is remarked by Hooker 
that the universal presence of this invisible vegetation throughout the South 
Polar Ocean is a most important feature, since there isa marked deficiency in 
this region of higher forms of vegetation ; and were it not for them there would 
neither be food for aquatic animals nor (if it were possible for these to maintain 
