138 Analysis of Scientific Books. 



insects enumerated, is certainly a curious fact developed by this 

 investigation. 



Sir Everard concludes this Lecture (which is illustrated by some 

 good engravings from Mr. Bauer's drawings), with the following 

 remarks : — 



" Having ascertained that in all the animals, the structure of 

 whose nervous system has been explained in the present Lecture, 

 the brain is a distinct organ, varying in its size it is true, till at 

 last it is scarcely distinctly visible to the naked eye, but when ex- 

 mined in the microscope, found to consist of globules and elastic 

 transparent matter, and more or less of a fluid, similar to the brain 

 of animals of the higher orders; that there is also, at some dis- 

 tance from the brain, a second substance of similar structure, con- 

 nected with the brain by two lateral chords ; and that this second 

 part gives off the nerves that go to the different muscular structures 

 of the body ; I consider myself borne out in the opinion that this 

 part answers the same purpose as the medulla spinalis. 



" The ganglions which form a chain connected so beautifully 

 together by a double nerve, must be considered to have the same 

 uses, whatever they are, as the ganglions in the human body, be- 

 ing equally composed of a congeries of nerves. These are facts, 

 which, if they are allowed to be clearly made out, form aij addi- 

 tion to our knowledge, and give confirmation to opinions not be- 

 fore satisfactorily established." — P. 7. 



2, Observations on the Migration of Birds. By the late Edward 

 Jenner, M.D., F.R.S. 



The late Dr. Jenner's paper on the Migration of Birds is chiefly 

 intended to develop some facts which he considers as hitherto 

 unnoticed respecting the cause which excites the bird, at certain 

 seasons of the year, to quit one country for another ; he, however, 

 assigns several preliminary pages to prove the " reality of migra- 

 tion," the fact itself not being, he says, generally admitted. To 

 the many well known instances proving the ability of birds to take 

 long flights. Dr. Jenner adds several others, chiefly with a view to 

 disprove the reality of the hibernating system, or the hypothesis 

 of a state of torpor. He also notices a fact not a little remarkable, 

 which is, that several birds which absent themselves at stated 

 periods, return annually to the same spot to build their nests. 

 This he proved by cutting of the claws of certain swifts, and find- 

 ing the birds thus marked for several succeeding years in their 

 nesting places. The silly supposition maintained by the late Dr. 

 Beddoes and others, that swallows and otlier birds, submerse 

 themselves in ponds and rivers, and there become torpid, we do 

 not think it requisite to combat, neither shall we quote Dr. Jenner's 

 experiment upon the drowning of a swift to controvert the notion, 



