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REVIEWS. 



Principles of Comparative Physiology. By W. B. Carpenter, M.D., 

 F.R.S. Fourth Edition. London. Churchill. 



Although it be an ample apology for the use of the micro- 

 scope, that he who records a new observation by its aid has 

 added another fact to science, yet we would fain hope that all 

 who use this instrument are more or less impressed with the 

 truth, that by its employment large departments of human 

 knowledge are being moved on. If we wanted an apology for 

 the use of the microscope, we could not do better than point 

 to the works of the learned and laborious President of the 

 Microscopical Society on the various branches of the great 

 science of Biology. Let any one compare the manuals of 

 Physiology that were in use twenty-five years ago with the 

 last editions of Dr. Carpenter's beautiful volumes, and they 

 will see not only how our knowledge of the laws which govern 

 vital phenomena has advanced, but they will see that it has 

 been mainly by the aid of the microscope. They will see too 

 in Dr. Carpenter's volumes how the labours of the humblest 

 observers become in time part and parcel of the great body 

 of special and general facts, which constitute the principles of 

 science. This should be an encouragement to all to persevere 

 in a course of observation, and to record what they liave ob- 

 served. Few perhaps know tlie whole value and significance 

 of the facts which are presented to their senses ; but if they 

 record them, they become appropriated by those whose special 

 and peculiar gift it is to generalise, and thus to give a form 

 and body to science. Of modern writers and workers few 

 possess this gift to so great an extent as Dr. Carpenter, and he 

 may be justly regarded as the most successful exponent of 

 Physiological science in this country, and one of our most 

 elegant scientific writers. The volume, whose name stands 

 at the head of our article, is intended as a companion to two 

 others, the ' Principles of Human Physiology' and the ' Prin- 

 ciples of General Physiology.' Tlie latter work, which is not 

 yet published, together Avith the present volume, formed the 

 basis of tbie author's ' Principles of Physiology, General and 

 Comparative,' which will henceforth cease to appear as a 

 single volume. 



In the present volume, which is devoted to the department 

 of comparative anatomy and physiology, the author has 



