MOVEMENTS OF VOLUNTARY MUSCLE. 
461 
Table. (Continued.) 
Diameter of primitive 
fasciculi in fractions of 
an English inch. 
Average diameter of same 
in the class. 
Insects < 
^Staghorn Beetle ( Lucanus Cervus ) . . 
“ Water Scorpion” ( Nepa cinerea) . 
“ Water Spider ” ( Gerris lacustris) . 
“ Harry Longlegs ” ( Tipula ) 
Carabus nemoralis 
“Blue Bottle Fly” (Musca vomitoria) 
1 tn 1 
10 3 1 0 
1 
200 
1 
250 
I 
500 
1 f-r) 1 
5 41 LU 3 7 7 
1 tn 1 
7 55 10 TOO 
'i 
s._i 
■419 
From this it would appear, that the average diameter of the fasciculi in the Human 
female is upwards of a fourth less than in the male, and that the average of both 
together is greater than that of other Mammalia. The class of Fishes has fasciculi 
nearly four times the thickness of those of Birds, which present the smallest of all. 
Next to Fish come Insects, then Reptiles, then Mammalia. In each of these dif- 
ferent classes an extensive range of bulk is observable, some fasciculi being three, 
four, or more times the width of others. In the above measurements, precautions 
have been taken to include only specimens in an uncontracted state, the importance 
of which will be seen in the sequel. 
Of the Transverse Strive. 
A decisive characteristic of voluntary muscle consists in the existence and close 
arrangement of alternate light and dark lines, discoverable only by the microscope, 
and of exquisite delicacy and finish, taking a direction across the fasciculi. These 
lines are so uniformly present, both in recent muscle and in that which has been pre- 
served, either by drying, or in alcohol, solution of alum, corrosive sublimate, or in 
various other ways, that it is most important to understand correctly their real 
nature. Their existence was doubtless known to Hooke, and Leeuwenhoek has given 
more than one very accurate description of them, as well as made constant reference 
to them in his letters. He believed, during the earlier years of his inquiry, that they 
were circular bands or girths, surrounding a bundle of fibrillse ; but at a later period 
he regarded them as of a spiral shape, and endeavoured to show, by a fancied ana- 
logy with an elastic coil of wire, that they were in some manner the originators of 
motion. Prochaska seems to have considered them to arise from a series of minute 
flexuosities of the fibrillse, caused by impressions made upon these by the contact of 
the filamentous and capillary tissues, which he fancied to penetrate into the interior 
of the fasciculi and invest each fibrilla. But in endeavouring to sustain an erroneous 
hypothesis of muscular action, he deceived himself into the opinion that these so- 
called flexuosities were the same, in kind, with secondary inflexions of the whole 
fasciculus, and with those zigzag bendings to which Prevost and Dumas have in later 
