LIST OF ILLUSTRATIONS xiii 



F1GUBE PAGH 



113. Longitudinal section of a trabecula of Limulus (King crab) heart 

 muscle, showing an intercalated disk separating a contracted 



from an uncontracted portion ...... 103 



1 14. Semidiagrammatic illustrations of various types of intercalated disks 104 



115. Successive stages of skeletal muscle histogenesis in mammals . 105 

 116. Transverse section of a striped muscle fiber of a newly-hatched rain- 

 bow trout, showing the process of myofibril increase by radial 



longitudinal splitting ........ 105 



117. Striated muscle fibers ruptured by teasing, showing the sarcolemma 106 

 118. Isolated fragments of striated muscle fibers, unstained . . 107 

 119. Striated muscle libers of the dog, seen in transection . . . 107 

 120. A portion of a striated muscle fiber seen in longitudinal section . 108 

 121. A small portion of a muscle fiber of a crab showing beginning separa- 

 tion into fibrils ......... 108 



122. Fibrils from the wing muscles of a wasp 109 



123. Longitudinal section of a portion of a striped muscle trabecula of 



Limulus, showing a nucleus of serrated contour with the telo- 



phragmata attached to the serrations . . . . . 109 



124. Striated fiber from a leg muscle of the sea spider (Anoplodactylus 



lentus), showing the complexly striped condition characteristic 



of insect muscle 110 



125. Semidiagrammatic drawing, representing the appearance of the 

 same fiber from the leg muscle of a beetle in ordinary and polarized 



light 110 



126. Lateral contractive wave of Cassida equestris . . . .111 



127. Striated muscle fibers of the dog 112 



128. Striated muscle of a cat seen in transection . . . .113 



129. Motor end-plate on an intercostal muscle fiber of a young rabbit . 115 



130. Portion of a transection of a large tendon ..... 116 

 131. Transverse section of tendon of tail of adult mouse . . .116 



132. Portion of a muscle fiber from the tail of a 5 cm. frog tadpole . 117 



133. Diagram of a neuron 120 



134. A unipolar ganglion cell of a frog 122 



135. Multipolar ganglion cell from the ventral horn of the gray matter of 



the spinal cord of the ox . . . . . . .122 



136. Pyramidal multipolar nerve cell from the cerebral cortex of a mouse 123 



137. Isolated nerve cells from the spinal cord of man .... 124 



138. Various types of nerve cells of the cerebellar cortex . . . 125 

 139. Three types of nerve cells supplying respectively cardiac (1), smooth 



(2) and (3) striated muscle . . . . . . .126 



140. A nerve cell from the trapezoid nucleus in the midbrain of a rabbit 127 

 141. A neuron (giant pyramidal cell, or cell of Betz) from the cerebral 



cortex of man, showing the neurofibrils 128 



