The President's Address. 
137 
rent colour by interference of the undulations of the luminous 
rays ; hence tlie tint assumed is to a certain extent an indi- 
cation of tlie mutual proximity or remoteness of the mark- 
ings on the various frustules. 
The next paper on my list is Professor Henfrey's "Notes 
on some fresh-water Confervoid Algae,, new to Britain/^ being 
descriptive accounts of the Pandorina morum of Ehrenberg, 
the Apiocystis Brauniana of Nageli, and the Clathrocystis 
aeruginosa, Henfrey = Microhaloa (sruginosa, Kiitzing^ which 
that observer can only have seen, as Mr. Henfrey considers, 
in a dried state, as it does not agree with Kiitzing^s descrip- 
tion of the genus referred to. 
As might have been predicted, Mr. Henfrey^s descriptions 
are careful and minute ; he has, however, erred in classing 
Pandorina morum amongst the Algae new to Britain, it being 
one that I myself, and I believe many other microscopists, 
have met with very frequently for the last ten years or more. 
Mr. Henfrey has, however, corrected the inaccurate account 
of the organization that was hitherto generally received. 
It will be as well to consider the three next papers together, 
for though each has its distinctive peculiarities, they all bear 
closely upon the same important subject, viz., the early 
stages of the vegetable cell. 
The papers are — ''On the Vegetable cell,'' by Mr. F. H. 
Wenham ; '' Brief remarks upon Cell-growth in the Bryonia 
dioica/' by Mr. Norris F. Davey; and "Vegetable Cell- 
structure and its formation, as seen in the early stages of the 
growth of the Wheat plant,'' by the Hon. and Rev. Sidney 
Godolphin Osborne. 
All of these papers tend to controvert the cell-theory of 
Schleiden and Schwann, so far as the doctrine of multipli- 
cation by self-division from unity is concerned ; and from the 
careful observations made by Mr. Wenham on the Anacharis 
alsinastrum, an aquatic plant, confirmed by those of Mr. 
Davey on a terrestrial one — the Bryonia dioica — it is abun- 
dantly manifest that simidtaneous development of many cells 
obtains, as one mode, at least, of increase. Of course it is 
not contended that increase by simple division does not take 
place, but that this is not the only, or, according to Mr. 
Wenham, the principal method of multiplication. When a 
somewhat startling statement is made by a microscopic ob- 
server, the first question which naturally occurs to the mind 
is this, Does he understand the manipulation of the in- 
strument? and the next. Can he rightly interpret Avhat he 
sees ? Now every one who is familiarly acquainted with Mr. 
Wenham, must, without hesitation, answer both these ques- 
