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PROCEEDINGS OF THE SOCIETY. 
Meeting of 17th December, 1890, at 20, Hanover Square, W., 
Prof. Urban Pritchard, Vice-President, in the Chair. 
The Chairman having declared the meeting to he made special for 
consideration of matters adjourned from the adjourned special meeting 
held 19th November, the Secretary said that the Council were still 
unable to recommend any course of action on the matters under 
consideration, and therefore advised that the adjournment of the special 
meeting be sine die. 
It was moved by Mr. J. M. Allen, seconded by the Rev. Canon 
Carr, and resolved, “ That this special meeting be adjourned sine die .” 
The Minutes of the meeting of 19th November last were then read 
and confirmed, and were signed by the Chairman. 
The List of Donations (exclusive of exchanges and reprints) received 
since the last meeting was submitted, and the thanks of the Society given 
to the donors. 
Six Slides of Leptodora hyalina 
Slide of Ceratium longicorne 
Three Lithographs of Fresh- water Sponge 
Two Photomicrographs of ditto 
From 
Mr. T. Clarke. 
Mr. J. Clark. 
Mr. T. Clarke’s letter relating to his donation of slides was read. 
Mr. Joseph Clark's description of his lithographs and pliotomicro- 
grajihs w T as read. 
Mr. G. F. Do wdes well’s note was read with reference to a small 
eye-piece thread-micrometer which he had sent to the meeting for 
exhibition, and which he stated was made about five years ago, and em- 
bodied the same principles as the one exhibited by Mr. Nelson at the 
meeting of the Society in May, and described in the August number 
of the Journal. A short further communication from Mr. Dowdeswell 
was also read in reply to some observations and inquiries with reference 
to the “ simple form of warm stage,” exhibited and described at the 
meeting of the Society in October last. 
Mr. J. Mayall, jun., said he thought that the means by which it was 
proposed to keep this stage warm — i. e. by applying a small flame below the 
projecting corner of it — were not sufficiently precise to render it possible to 
keep the temperature within a variation of one degree, as suggested by 
Mr. Dowdeswell. According to the opinion of Dr. Dallinger it was of 
the utmost importance, that in all observations bearing upon the influence 
of temperature on the forms of life and development, the means of 
regulating and maintaining the temperature of the stage should be 
absolutely under control, and he feared this could hardly obtain with 
the method described by Mr. Dowdeswell. 
Mr. E. M. Nelson having examined the micrometric eye-piece, said it 
appeared to him to be a *• Jackson eye-piece micrometer,” and that was 
