Xii LIST OF ILLUSTEATIONS 







FIGURE PAGE 



85. Notocbordal tissue . ...... 72 



86. Transection through the compact bony wall of a human meta- 



carpal bone ...... 73 



87. Longitudinal section of ground bone from the shaft of the human 



femur . . . . ... 74 



88. Isolated bone cell shrunk away from wall of its lacuna . 75 



89. An Haversian system, including the central canal, several lamellae, 



lacunae and canaliculi .... ... 75 



90. Transverse section of Haversian canal, with contents ... 76 

 91. The primary changes in intracartilaginous bone formation . . 80 

 92. A longitudinal section of the two distal phalanges from the finger 



of a five-months' human fetus . . ... 81 



93. Reconstruction of cartilage into bone ..... 82 



94. Trabecula of primary enchondral bone, showing a central deep- 

 staining core of calcified cartilage and a peripheral layer of osteo- 

 blasts . ... .83 



95. Trabecula of primary bone from the finger of a human fetus 84 



96. Intramembranous bone formation in the lower jaw of a sheep fetus 87 

 97. Smooth muscle cells ........ 91 



98. Smooth muscle cells from the pig's stomach .... 92 



99. Smooth muscle cells from the wall of the human intestine . . 92 

 100. Smooth muscle cells from the wall of the human intestine . . 93 

 101. Two stages in the histogenesis of smooth muscle, from the wall of 



the esophagus of a pig embryo . . . .94 



102. A group of myoblasts from the heart muscle syncytium of a 48-hour 



chick embryo ......... 95 



103. Cardiac muscle of guinea-pig, showing several branches, cross 



striations (ground membranes) and a number of intercalated disks 95 

 104. Cardiac muscle cells from the pig's heart, isolated in equal parts of 



alcohol, glycerin, and water ...... 96 



105. Cardiac muscle of the human heart; the abundant branches are 



plainly shown ... 97 



106. The central portion of figure 5, more highly magnified ... 98 

 107. Transection of a group of cardiac muscle fibers from a papillary 



muscle of the human heart ... . .98 



108. Developing muscle fibers from the heart of a human fetus at 



seven months ... ... 99 



109. Cardiac muscle fibers ... . 100 



1 10. Diagram of a striped muscle fiber, according to Heidenhain . . 101 

 111. Six-lobed nucleus from the heart muscle of Limulus, showing the 



continuity of the nucjear wall with the telophragmata . . 101 

 112. Seven nuclei, the product of amitotic division, lying in an undifferen- 



tiated mass of sarcoplasm, from the heart of Limulus . . 102 



