602 Chronicles of Science. | Oct., 
Y Anatomie,’ entitled “ Pictorial Studies (dudes graphiques) on the 
Nature of Muscular Contraction.” The instrument used in these 
investigations is called a myograph, and consists of a sort of spring 
clamp by which the muscle is lightly grasped and so arranged that 
any variation in the tension of the arms of the clamp shall effect 
the continuity of a galvanic current. The variation in the galvanic 
current is made to exhibit itself in the movement of a pencil, by 
which the myogram is written, asin thesphygmograph. Dr. Marey 
considers that voluntary muscular contraction is a complex pheno- 
menon, resulting from the fusion of a series of successive “ agitations.” 
A muscular agitation is the movement which one observes under 
the influence of a single electric or traumatic excitation directed on 
a nerve ora muscle. It is most necessary to distinguish between 
this phenomenon and contraction, of which it is only an element, 
in the same way that a vibration is one of the elements of a sound. 
The characters of these muscular agitations can be determined by 
the myograph, and are found to vary under the influence of fatigue. 
A definite number is necessary to produce contraction of the 
muscle, but the number varies according to the animal and to the 
condition of fatigue. Helmholtz considered that 32 agitations in 
the second were necessary for tetanization, that is, complete con- 
traction; but M. Marey shows that in a bird 75 may be necessary, 
and in a tortoise only 4. He regards the systole of the heart as a 
single “agitation ” (secousse). 
Dr. Charlton Bastian in the last number of the ‘ Quarterly 
Journal of Microscopical Science, has entered into a minute 
description of, the curious little granular bodies occurring on the 
surface of the brain, first described by Antonius Pacchionius, and 
known as Pacchionian bodies. Much laxity and carelessness has 
hitherto existed in reference to these bodies. By Pacchionius they 
were called glands, but this soon proved to be incorrect, though 
their true structure was never demonstrated. Many authors 
regarded them as arising from the pia mater beneath the arachnoid. 
Dr. Bastian shows that these growths are invariably developments 
from the visceral arachnoid, and has demonstrated that they have 
a complete epithelial covering and a fibrous structure agreeing 
with that of the arachnoid. Dr. Bastian’s conclusions were 
anticipated to some extent by Ludwig Meyer, in a recent number 
of ‘ Virchow’s Archiv.,’ but this does not detract from the value of 
his independent research. 
The second volume issued by the Ray Society to its subscribers 
for the year 1866, is a series of translations from the Scandinavian 
languages of recent memoirs on the Cetacea, by W. H. Flower, 
F.R.S. The first is “ On the Greenland Right Whale” (Balena 
mysticetus), by D. F. Eschricht and J. Reinhardt, originally 
published in 1861. No other complete description of the osteology 
