120 METHODS OP MICROSCOPICAL RESEARCH. 



thin so thin, indeed, as to obliterate all the features 

 and structure which it is necessary to study in order 

 to arrive at the physiological or biological elements 

 of the specimen. Brain, spinal cord, and the like 

 tissues, for example, cannot be cut too thin kidney 

 and several other organs can easily be so, and thus 

 be rendered worthless for purposes of study. It is 

 well, therefore, to provide one's self with three 

 sections of such specimens, as it may be found 

 possible, by experience, to cut too thin ; so that for 

 general observation and study, with low powers, a 

 thin section is at hand, for medium powers a thinner 

 section, and the thinnest for use with high and the 

 highest powers. 



Some writers and practical workers assert that 

 it is not possible to cut the thinnest sections from a 

 celloidin-embedded specimen by the ether freezing 

 process ; the author can only say that he has cut 

 sections of entire human eyes, so embedded and 

 frozen, sireoths of an inch thick (or rather thin), 

 and of brain and spinal cord, &c., jcfeoth of an inch 

 thin. 



For cutting sections by the ether freezing process 

 there is (with the exception of the automatic Minot 

 microtome recently produced and fully described in 

 later pages) no better microtome than the Cathcart, 

 as perfected and supplied by Mr. Alexander Fraser, 

 of Edinburgh (which is fully described and illustrated 

 on pages 127-8), with admirable arrangements and 

 apparatus for embedding specimens in paraffin and 

 for cutting those also, the freezing and this arrange- 

 ment being removable at will and interchangeable. 



