1882.] 



MICKOSCOPICAL JOUKIS-AL. 



169 



penditure of twenty-five cents, the 

 tissues to be operated on, can be 

 kept frozen for several hours at a 

 time. Small objects immersed in 

 gum solutions, are frozen and in con- 

 dition for cutting, in less than one 

 minute. 



The method of using this micro- 

 tome can be understood by reference 

 to the illustration. A represents a 

 revolving plane, by which the thick- 

 ness of the section is regulated, in 

 the centre of which an insulated 

 chamber is secured for freezing the 

 tissue. It resembles a pill-box con- 

 structed of metal. A brass tube en- 

 ters it on each side. The larger one 

 is the supply tube, and communicates 

 with the pail a, situated on bracket s, 

 by means of the upper tube /. To 

 the smaller brass tube is attached the 

 rubber tube / b, which discharges the 

 cold salt water, into a pail placed 

 under it. (See b.) The salt and 

 water, as it passes from pail a to 

 pail b, is at a temperature of about 

 zero. The water should not be allow- 

 ed to waste. It should be returned 

 to the first pail for continual use, or as 

 long as it has freezing properties. As a 

 matter of further economy, it is neces- 

 sary to limit the rate of exit of the 

 freezing water. This is regulated by 

 nipping the discharge-tube with the 

 spring clothes-pin supplied for the 

 purpose. Should the cold within the 

 chamber be too intense, the edge of 

 the knife is liable to be turned and 

 the cutting will be imperfect. When 

 this occurs the flow of water through 

 the chamber is stopped by using the 

 spring clothes-pin as a clip on the 

 upper tube. In order to regulate the 

 thickness of the tissue to be cut a 

 scale is engraved on the edge of the 

 revolving plate A, which, in conjunc- 

 tion with the pointer e, indicates the 

 thickness of the section. 



Prof. D. P. Penhallow read a paper 

 " On Some Peculiarities Incident to 

 the Diseases of Fruits," of which we 

 have no abstract. The paper treated 

 mainly of the results of chemical 

 analysis. 



Mr. C. E. Hanaman described a 

 " Filtering Wash-bottle Especially 

 Adapted to the Use of the Histolo- 

 gist." It is intended to hold the re- 

 agents and staining fluids in common 

 use. It consists of a Wolfe's bottle 

 with tubes arranged as in a chemist's 

 wash-bottle, so that when air is forced 

 into one tube the fluid is forced out 

 of the other. The first tube is pro- 

 vided with a rubber pressure-bulb 

 for compressing the air ; the second 

 supports a filtering tube filled with 

 cotton, so that the reagent is always 

 obtained free from suspended 

 particles. 



Mr. J. H. Pillsbury read a very in- 

 teresting article, which was a portion 

 of a more comprehensive paper, "On 

 the Development of Cilia in the 

 Planula of Clava leptostyla." We hope 

 to print this contribution in a future 

 number, but it requires illustrations 

 which (iannot be prepared in time for 

 this issue. 



Prof. W. H. Seaman, read a paper 

 of which the following is an abstract 

 prepared by the author : — 



A FUNGUS ON THE LEAVES 

 OF PEAR TREES. 



In 1865 and 1876 my attention was 

 directed to numerous small, black 

 dots with which the leaves of pear 

 trees in the vicinity of Washington 

 were covered, A slight examination 

 showed me that the fungus (for such 

 the dots proved to be), was as yet 

 undescribed in the books, and I im- 

 mediately endeavored to ascertain if 

 it had been previously seen by ob- 

 servers. After some correspondence, 

 I found that the Rev. J. L. Zabriskie, 

 of New Baltimore, New York, had 

 specimens of similar character, col- 

 lected by Rev- R. G. Strong, in 1873, 

 on the leaves of quince. Mr. Zabris- 

 kie published a short description of 

 his specimens on little slips of paper, 

 which he distributed to a few friends, 

 and which so far as I know, is the 

 only printed notice of this pest. The 

 slip is as follows : — 



Blastesis, new genus. — Perithecia 



