ToMKiNs^ on a new Diatom-Finder. 
57 
boy who has long been suffering from a scaly disease affecting 
the whole of the cutaneous surface. In some respects it 
resembles favus, and the crusts^ which fall off in immense 
quantities,, resemble the Anchorion Schoenleinii, in fact are 
wholly composed of torulse and epithelial scales. A small 
piece of crust put into sugar and water passes through the 
usual stages of the fermentative process^ and gives off car- 
bonic acid. Any quantity of sweetwort might be fermented^ 
indeed the scales look like dried yeast ; proving the analogy 
between this fungus and the yeast-plant. 
On a New Diatom-Finder. By J. N. Tomkins^ Esq. 
I BEG to offer this simple^ yet efficient^ instrument to the 
notice of the Society, especially to those of its members who 
are interested in the study of the Diatomacese. The idea 
is taken from Dr. Carpenter^s description of Gairdner^s 
Simple Microscope'^ [vide ^ The Microscope and its Revela- 
tions/ p. 66, fig. 17), but with some, not unimportant, 
alterations ; a " Coddington^' is substituted for the series of 
single lenses or doublets employed, while the well-known 
" Varley^s Animalcule-cage'' is applied as the object-holder ; 
the method of focal adjustment remaining the same (in prin- 
ciple) as in the " Gairdner." 
The advantages attempted to be gained by these alterations 
are, — a larger andbetter illuminated 'Afield'' than is consistent 
with the employment of the single lens or doublet, yet with 
sufficient magnifying power to answer the purpose intended ; 
the animalcule- cage also affording a ready means of sub- 
jecting the water under examination to the condition of a 
thin film, owing to the capillary action exerted by the ap- 
proximation of the opposed glasses. 
The readiness with which the cleansing of the glasses is 
effected preparatory to the examination of a fresh specimen, 
will be best appreciated by any one who has attempted (as I 
