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employment of Curare in this investigation, under the action 

 of which voluntary movements cease, while the circulation 

 goes on unimpaired. In the curarized frog we are enabled 

 to explore the phenomena of the capillary circulation for 

 many hours with the greatest precision ; — to watch the first 

 commencements of inflammation ; to observe the effects of 

 poisons on the blood-vessels ; to ascertain the laAVS of those 

 movements of contraction and expansion, which regulate 

 the whole process of nutrition ; in short, to establish a host 

 of facts of fundamental importance in physiology and 

 pathology. 



All conclusions, however, which are derived from observa- 

 tions of animals far down in the scale are subject to the 

 objection that their functions are carried on under conditions 

 considerably remote from those which exist in man. It 

 has, therefore, been long desirable to change our field of 

 research to mammalia. Hitherto only one mammalian 

 animal has lent itself to this purpose, — the bat. To the use 

 of the bat's wing, however, there are objections which will 

 never be overcome, chiefly because it is covered with an 

 integument so thick, that although the vessels can be seen, 

 the tissues around them are indistinguishable. 



It was, therefore, clearly necessary to look in other direc- 

 tions. To this work we set ourselves at the beginning of 

 last month, — both of us with a practical, i.e. pathological 

 object in view, — one of us with a view to his researches on 

 inflammation, the other with reference to inquiries about 

 tuberculosis. 



The first requirement was a suitable animal, the second an 

 anaesthetic, the third a method of placing the tissue to be 

 explored under the microscope. 



We will begin by speaking of the anaesthetic. 



It Avas at once obvious that, the bat being discarded, no 

 other mammal could be procured in which any external part 

 is sufficiently transparent for observation under the higher 

 powers of the microscope. Therefore, the method must 

 necessarily involve the use of the knife, i. e. (let us not 

 shudder at the ugly word) vivisection. Hence an anaesthetic 

 was absolutely necessary. Most happily chloral was found 

 to be complely adapted to our purpose. About three grains 

 of chloral under the skin we found to be sufficient to render 

 a full-sized guinea-pig motionless and insensible for many 

 hours. 



Next the selection of an animal was to be considered. 

 This Avas not difficult. One of us (Dr. Sanderson) was fami- 

 liar with the remarkable structure of the guinea-pig's 



