14 
LE. 
INTRODUCTION. 
muscles with varicose structure of the primitive fibres, and 
fine transverse stripes of the primitive bundles. This is 
the structure of the muscles of voluntary motion amongst 
vertebrate and articulate animals, and of the muscles of the 
heart. These fibres are very fine, 4, millim. and less, and 
are amongst the finest parts of the animal organism. Other 
muscles consist of coarser fibres 4,...35 millim. which are 
not jointed or varicose, and which correspond to the primi- 
tive bundles of the former. In these therefore no transverse 
stripes are seen. To these belong the muscular fibres of the 
intestinal canal, also the red fibres of the muscular stomach 
of birds. Usually these muscles of organic life have a 
pale and somewhat yellow colour. Muscular tissue has the 
property of contracting, upon the application of a stimulus, 
in the direction of its fibres. This irritability (¢rritabilitas) 
is a vital property, and is distinct from the elastic contrac- 
tility, which other parts of the body retain even after death. 
Llastic Tissue (tela elastica). This tissue has much resem- 
blance to conjunctive tissue, and holds, as it were, an inter- 
mediate position between it and muscular tissue. The fibres 
are of unequal size (5... millim.) and have a serpentine 
course: they divide frequently and unite at many points with 
branches from other fibres, whence a reticulate distribution 
arises. The colour of this tissue is yellow: it retains its 
elasticity unaltered by keeping in spirit of wine, or by 
boiling for several days. After long boiling it gives a small 
quantity of a peculiar glue which in some points agrees with 
eartilage-glue. The cervical ligament of mammals is com- 
posed of this tissue: also in arteries a layer of elastic fibres 
lies between the circular fibrous coat and the external coat 
of cellular tissue: in large trunks this layer may be clearly 
distinguished as a continuous membrane. The yellow 
ligaments on the arches of the vertebrae, and the ligaments 
of the trachea, also consist of elastic tissue. But not merely 
as separate ligaments or membranes, but also mingled with 
other tissues, elastic fibres are met with in different situa- 
tions, as for instance, in serous membranes and in skin. 
We have here spoken only of those tissues which occur most 
generally. We have not noticed Dental Tissue because, whilst we 
