440 
NATURE 
theoretical subjects, there are many statements to which 
we must take exception. Most of the theories bearing 
on some of the main problems in the circulation of the 
blood, are at the present day in too unsettled a state to 
find a place in a manual for students, because it is im- 
possible in the permissible space to give the many con- 
flicting results of different authors, which yet remain 
unproved or unrefuted. The result is, as might be 
expected, that a one-sided and individual view of the 
subject is presented, and the student is taught some 
things which he will have to unlearn. Most of Dr. San- 
derson’s theories have already appeared, but nevertheless 
some are based on principles undoubtedly unsound. 
Whilst discussing the expansive movements which 
occur in an artery during the different parts of the pulse 
beat, and the cause of the variations in the extent of the 
changes in diameter of the arteries which may be ob- 
served, the following occurs :—“A moment’s considera- 
tion teaches us that there are two circumstances which 
must diminish the minimum pressure in the arteries, viz., 
diminution of the mean arterial pressure, and prolongation 
of the period which intervenes b2tween one’expansive act 
and its successor. In other words, the less frequent the 
Sahin oh, 
Fic. 2.—Dissection of the parts in relation with the vagus nerve of the frog 
on the right side. The oesophagus is distended with a glass tube about 
half-an-inch in width. The object is represented of about twice its actual 
size. a, right aorta ; B, dudbus aorte: c, posterior horn of the hyoid 
bone; gf, genio-hyoid muscle ; 4g, hyo-glossus muscle; /, lowest of 
the three petrohoid muscles; H, ninth nerve; G, glossopharyngeal 
nerve; 7, vagus; 0, larynx; s& 4 &o%, poiat to the space occupied by 
the origias of the large muscle (sternohyoid) which connects the hyoid 
with the sternum, as well as by the omohyoid ; both of these muscles 
have been cut away. 
contractions of the heart and the lower the arterial pressure, 
the greater the expansion in proportion to the expa nding 
force which produces it” (the italics are not ours). Dr. 
Sanderson would undoubtedly thus lead us to believe 
that this is a self-evident proposition, but that it is so is 
far from the case. That it should be true it has to be 
assum2d that the escape of blood from the peripheral 
vessels between two succeeding pulse beats, depends on 
the interval which elapses between them, and no attempt 
is made to prove this fact, whichis not at all necessarily 
correct, and against which many arguments can be 
adduced. The same author also adopts a modification 
of the now antiquated and decidedly insufficient oscillatory 
hypothesis, to account for the dicrotic beat of the pulse, 
so clearly seen in the sphygmograph trace: and in so 
doing he necessarily ignores the great value of the im- 
portant and very definite results obtained by Chauveau 
and Lortet, by means of their hanadromograph; if he 
had fully realised the easily demonstrable fact that the 
second rise in the sphygmograph trace commences the 
later in an artery according as it is farther from the heart, 
the table on p. 228 referring to the relations of the different 
elements of the pulse beat in differeat vessels could not 
have appeared in its present form. As long as physio- 
logists compare arteries to elastic stubes in air, they 
must be led into error, for the forces which predominate in 
them so situated, are very different from thos? which 
prevail’ when they are surrounded by water or any 
yielding substance, which an artery much more directly 
resembles, as it is surrounded by, and on most sides in 
contact with, tissues of a somewhat yielding nature. 
There is another short sentence we must quote; in ex- 
plaining the action of the auriculo-ventricular valve we 
read: “The time which intervenes between the com- 
mencement of the compression and the tightening of the 
valve varies according to the vigour of the contractions, 
the quantity of the blood contained in the ventricle, and 
the previous position of the valve, must always be appre- 
ciable.” Does the author really wish us to believe that 
the heart, a powerful muscular pump, which he affirms 
(though on very slight grounds) acts most powerfully at 
the commencement of each beat, requires an appreciabl 
time, by which we understand, one thit can be measured 
by instruments at our command, to tighten the auriculo- 
ventricular valve, against which the resistance is undoubt- ~ 
edly extremely small? it seems very improbable. 
Fic. 3.—The marking lever for indicating graphically 01 a revolving drum 
the moment at which an electric current is broken. 
The chapter on animal heat contains much useful 
information, but several of Senator’s results are not en- 
tered into, and I.aschkewitsch’s explanation of the fall 
of temperature in “varnished” rabbits, which are dis-~ 
cussed in detail, is not given. None of the special pre- 
cautions which have to be taken in employing the mercu- 
rial thermometer for physiological investigation, are 
referred to; and the student will be entirely misled 
respecting the principle upon which the ordinary 
clinical thermometer of Phillips is constructed, the 
author having muddled up with his description Hawks- 
ley’s method for preventing the index running into the 
bulb whilst the operator is depressing it, which is entirely 
independent of, and has nothing to do with, the self- 
registering power of the instrument. A similar want of 
knowledge of physics is shown on the same page on which 
this error occurs, for it is stated that in the thermometric 
couple the degree of deflection of the galvanometer needle, 
which is produced when a current results from the un- 
equal heating of its ends, varies with the difference of 
the temperature of the junctions, which is well known to 
be incorrect. 
Dr. Foster, in undertaking the “ Functions of Muscle 
and Nerve,” has undoubtedly had a difficult work to per- 
form, and he has introduced a very clear and simple 
method of teaching the various, and in many cases, dis- 
[April 10, 1873 
