100 
Davey, on Bryonia Dioica. 
to assert that these plans are the best that can be devised. 
The subject is still open to improvement; but^ vrhatever 
modification is adopted_, in performance of our duty we 
strongly urge the necessity of basing them all upon one 
similar standard of measurement, taken from sl flawed point on 
the object-slide itself. If this be done_, objects registered by 
one observer may be found by another, though each may use 
a finder of a different form ; the difference affecting merely 
convenience in using. 
There is one observation arising from this subject, although 
not strictly a portion of it, which the Committee wish to 
make. If, by reason of defective workmanship, or errors 
caused by the use of adapters, different object-glasses are not 
in the same line of centre, a readjustment by means of the 
standard will be required on changing the objective. We 
therefore call attention to the great convenience it would be 
to all users of the microscope if every maker would adopt 
the same pattern for a screw, a proper steel gauge being 
provided for the purpose. At present it not unfrequently 
happens, on applying another object-glass to a microscope, 
that it has to be built upon a system of three or four 
adapters, to the manifest detriment of its performance. If 
all our principal makers will acquiesce in this, we shall be 
most happy to give our assistance in establishing the best 
form of screw. 
As our endeavour has principally been to determine the 
means by which a uniform system of registration may be 
obtained, we have not thought it necessary to make any 
critical inquiry as to the respective merits or defects of the 
plans already published ; we have borrowed freely from them ; 
and we have also received valuable practical suggestions from 
Professor Quekett and Mr. Hislop, for which we here tender 
our thanks. 
(Signed) George Jackson. 
Chas. Brooke. 
F. H. Wenham. 
Brief Remarks upon Cell-growth in the Bryonia Dioica. 
By NoRRis F. Davey, Esq., M.R.C.S. Eng. 
(Read June 25th, 1856.) 
Having been much interested by Mr. Wenham^s recently 
published views with regard to the development of vegetable 
cells, I felt a strong desire to repeat his observations. After 
having seen all that he describes in the Anacharis, it occurred 
