50 
The Presidents Address. 
Mr. Thomas Davies has employed photography to render 
the beautiful specimens of artificial microscopic crystallization 
which were engraved as illustrations in our Journal,, and Dr, 
W. Bird Herapath, in his valuable papers on the anchors and 
plates of various synaptee, and the pedicell arise of the echino- 
dermata, has likewise had recourse to photomicrography ; the 
photographs being reproduced as engravings and valuable 
illustrations in the Society^s Journal. 
In the person of Count Castracane we have the pro- 
mise of the subject being more fully worked out. He 
has started with the assistance of a Dubosc's heliostat and 
prism mounted so as to employ monochromatic light; 
possibly this may have its actinic advantages, as it occasion- 
ally has its optical, for we find both Mr. Wenham and Dr. 
Maddox calling attention to the use of coloured glasses over 
the eye-piece. Still, I learn from Dr. Maddox that in his 
trials with monochromatic light, as derived from the use of 
Abraham's condensing prism without heliostat, that he did 
not obtain any advantage, but rather, in some instances^ the 
reverse ; the field and object (when the latter is very trans- 
parent) being more or less of the same tint, which neutralized 
the contrast too much ; at least he found it did so for the re- 
production of transparencies for the lantern. 
Mr. Sorby, I believe, also employs photography to illustrate 
the appearance of fractured surfaces by reflected light. 
Probably many others are quietly at work on the subject, 
with the results of whose labours, sooner or later, perhaps 
this Society will be favoured. 
Abroad it has largely extended its influence, and it remains 
with ourselves to see whether we shall lose or retain our 
position. The hindrance to its being fully utilized appears 
to me greatly to arise from the expense attending the publica- 
tion of such illustrations as photographs, more especially in 
scientific literature. Possibly we are on the eve of being able 
to produce such (which seems highly probable from papers 
recently read at the meetings of the Photographic Society) 
by means more nearly allied to the ordinary methods of 
printing, and then we may expect its future will be as rapid 
as its past has been tardy. 
In a paper on the structure and affinities of the Polycystina 
Dr. Wallich has furnished us with an elaborate account of 
this obscure family of the Protozoa, and a classification based, 
as he believes, on the only constant characters it exhibits, 
viz., those involved in the mode of development and growth 
of the siliceous framework within and around which their 
soft part, or sarcode, is sustained. This is an important step 
