May 10, 1907] 



SCIENCE 



747 



SPECIAL ARTIGLE8 



THE ETHER FREEZING MICROTOME, IN BOTANICAL 

 TECHNIQUE 



The following description of a freezing 

 microtome, and its advantages, is published 

 in the hope that others will derive such 

 benefits and conveniences as I have for some 

 time enjoyed through its use. The microtome 

 is exceedingly simple, and so easily manipu- 

 lated that an inexperienced person may 

 quickly learn to operate it successfully. It is 

 very rapid in its work, allowing of sections 

 even in less time than is sometimes required 

 for free-hand sections, and does very efficient 

 work. In some kinds of material the sections 

 are superior to those obtained by the paraffine 

 method. It is useful in dealing with a great 

 variety of objects, and is cheap enough to be 

 within the reach of all. 



The freezing method of embedding in sec- 

 tion work is well known to all biologists, but 

 owing to the use of faulty or cumbersome 

 apparatus, or to the application toward inap- 

 propriate ends, it has not become as general 

 in use as it should be. Osterhout^ found the 

 freezing method absolutely necessary in the 

 anatomical study of the red sea-weeds. No 

 other freezing apparatus with which I am ac- 

 quainted combines the good features of the 

 machine described below, and I would espe- 

 cially call the attention of all scientists who 

 have used or are using freezing microtomes 

 to these features. The freezing device is ex- 

 ceedingly simple and effective. The knife 

 carriage is also very simple, is accurate in its 

 wori^ and although very rigid allows of sec- 

 tioning on any part of the knife, and at almost 

 any angle, vertical or horizontal with little 

 or no delay in adjustment. This latter feature 

 is especially valuable. 



It should, first of all, be explained that it is 

 not the intention of the writer to recommend 

 this method as a substitute for the paraffine 

 method. Messrs. Hill and Gardiner, however,' 

 have developed this freezing microtome tech- 

 nique in the examination of ' connecting 

 threads ' of pine tissues to a high degree of 



^Bot. Gaz., 21: 195, 1896. 



' See Philosophical Transactions of the Royal 

 Society of London, Series B, Vol. 194, pp. 83-125. 



proficiency, and it is to be hoped that their 

 results will be more widely applied. It is not, 

 however, in the study of cytological problems 

 that I have found the technique of most use — 

 though remarkable results have been obtained 

 by Hill and Gardiner — but it is in its use 

 in other lines that it has proved of very great 

 value. The method is capable of application 

 in so many ways, and for such a great variety 

 of purposes that an enumeration of these is 

 deemed advisable. It is chiefly useful for a 

 great deal of work where paraffine sectioning 

 is too slow, and where free-hand sections are 

 difficult to obtain; for example, in sections of 

 certain rust pustules. A great deal of time 

 can often be saved by preliminary sectioning 

 with the freezing microtome before using the 

 paraffine method, in order to determine the 

 condition of the material about to be used. 

 The freezing method can be so developed as 

 to give sections as quickly as, or even in less 

 time than, the free-hand method. The sec- 

 tions, moreover, can be produced in much 

 greater number and are far superior in thin- 

 ness and uniformity, and in certainty of suc- 

 cess. Material can be frozen in eight seconds 

 with an apparatus in good order, so that the 

 embedding can be accomplished in less time 

 than is required for the insertion of the same 

 in pith for free-hand work. 



Every mycologist knows how diffici;lt it is 

 to get sections of most fleshy fungi and 

 how almost impossible sections of sporophores 

 of the Tremellinese and teleutospore clusters 

 of Gymnosporangium are, yet these are cut 

 with greatest ease by the freezing method. 

 It is possible to cut a gelatinous sorus of 

 Gymnosporangium macropus from tip to 

 bottom together with the hard wood from 

 which the sorus arises, and to preserve it all 

 intact. This seems to me impossible by the 

 free-hand method, and the dehydration in the 

 paraffine method leaves the material in an 

 unsuitable condition for section work. Again, 

 objects of large size can be cut easily, such 

 as small phalloid ' eggs,' entire caps of small 

 agarics, small earth stars, etc., which, if cut 

 at all by the free-hand method would give 

 uneven sections, unless the manipulator is a 

 person of extraordinary skill. I have found 



