May 10, 1907] 



SCIENCE 



749 



give a better infiltration. It is then oriented 

 in a drop of ten-per-cent. gum arabic placed 

 on the small brass plate (a) in the center of 

 the table, and a spray of ether is atomized 

 against the corrugated under surface of this 

 plate, producing the necessary low temi)era- 

 ture. The atomizer is usually worked by 

 hand with a double bulb, but I have found a 

 compressed-air tank (such as physicians use) 

 a very great convenience, as such a tank 

 allows of the unhindered use of both hands 

 in the microtome work. It also admits of 

 more rapid freezing. I have been able with 

 this apparatus to freeze material in eight 

 seconds on a warm summer's days in Wash- 

 ington, D. 0. A foot pump may also be used 

 in place of the double bulb. The knife (f) 

 is carried by a shoe (6) and is held in place 

 by adjustable screws. The shoe is supported 

 by three bone-tipped adjustable screws, the 

 forward one of which (c) is used to set tha 

 knife after each stroke in preparation for tha 

 next one. The screws rest on a plate-glass top, 

 which covers the table around the central brass 

 plate. The smoothness of motion is facili- 

 tated by oil placed on the plate. The atom- 

 izer is of the ordinary type. The intake is 

 shown at (cZ), and the ether bottle at (e). 

 The ether should be of good quality (that used 

 in medicine for anesthesia) in order to obtain 

 the best results. 



The gum arable may be kept in stoppered 

 bottles, and can be preserved from mold and 

 bacterial attacks by adding a few crystals of 

 carbolic acid or thymol. The sections after 

 cutting can be handled in the ordinary way 

 with section lifters or with small sieve nets of 

 cloth or other substance. The latter method 

 is very useful if the sections are to be trans- 

 ferred to stains and afterwards washed. Very 

 delicate sections may also be handled by 

 means of a loop of fine platinum or brass 

 wire. The sections are caught up in the 

 water drop and are easily transferred to other 

 dishes or to a slide without the injury which 

 is liable to occur in handling with ordinary 

 section lifters. The sections may be mounted 

 in glycerine or glycerine jelly, and can then 

 be permanently mounted, without having 

 touched alcohol if water stains are used. As 



Hill and Gardiner point out, the dehydration 

 of sections in alcohol may leave protoplasmic 

 structures in a condition very different from 

 the normal. Of course, the effect of freezing 

 is also one which must be taken into account, 

 though this is seldom, if ever, a serious factor 

 in the morphological and anatomical work for 

 which this method is here recommended. Sec- 

 tions for ordinary anatomical work can be 

 cut from fresh material, or from dry material 

 after soaking in water. The material may 

 also be killed by the ordinary methods, pref- 

 erably without the use of alcohol, and may 

 then be washed in water in the usual way and 

 preserved indefinitely in a concentrated thymol 

 solution. Such material can be prepared for 

 the knife simply by washing carefully in 

 water. 



I wish to acknowledge that my acquaint- 

 anceship with the possibilities of the micro- 

 tome described above was made in the Cam- 

 bridge (England) botanical laboratory, and I 

 am indebted to Mr. A. W. Hill, of Cambridge 

 University, for many courtesies and favors in 

 my observations and study of this method. 

 E. M. Freeman 



U. S. Department of Ageicultube, 

 Washington, D. O. 



ASTRONOMICAL ISfOTES 



THE YALE PARALLAXES 



Transactions of the Astronomical Ohserva- 

 tory of Yale University. — Dr. W. L. Elkin, 

 director of the Yale Observatory, undertook, 

 in 1884, by means of the heliometer, the deter- 

 mination of the parallaxes of the ten stars of 

 the first magnitude in the northern sky. This 

 work was carried out with rare ability and 

 success during the following ten years; but 

 before the completion of this work, it was de- 

 cided to extend the research by undertaking a 

 survey of all rapidly moving stars not previ- 

 ously attempted, with a view to singling out 

 those which are near enough to show a measur- 

 able parallax. This work has been carried 

 on during the last thirteen years, and the 

 results have been recently published as 

 Volume II., Part 1, of the Observatory Trans- 

 actions, under the title, ' Parallax Investiga- 

 tions on 163 stars mainly of Large Proper- 



