XIV.] 



ORGANIC FUNCTIONS. 157 



indefinite power of growth that belongs to leaf-bearing 

 ones, and if they are supplied with abundant nourish- 

 ment, so as to cause them to grow rapidly, they cease to 

 bear flowers, and are changed back into leaf-bearing 

 branches. A still more remarkable instance of the same 

 kind is that of the worm-like larvae of some insects, which Insect 



, . • n r • metamor- 



at first feed voraciously and grow rapidly, iormmg com- phogis_ 

 paratively simple and undifferentiated structures : but 

 growth ceases when further development begins; growth 

 ceases when the larva enters into the chrysalis state, and 

 all the vital energies are employed in the work of develop- 

 ment, which consists in transforming the comparatively 

 undifferentiated tissues of the larva into the highly differ- 

 entiated tissues of the perfect insect. And not only so, 

 but the insect becomes inactive : motion ceases as well as 

 growth, in order apparently that no energy may be spared 

 from the work of development. As already remarked,^ it 

 is nearly impossible to doubt that some transformation Transfor- 

 of energy takes place in the act of development. If it is en^^iu 

 true that a charge of energy is taken up and becomes develop- 

 static in the act of unorganized material acquirmg organi- 

 zation, it appears probable that a further charge is taken 

 up in the act of development, which is the acquisition of 

 higher organization.^ 



The tissues which are differentiated from each other Formation 

 combine into organs. In some cases at least, there is no ^ ^^S^^^- 

 distinction between tissue-formation and organ-formation. 

 The shell of a moUusc, for instance, is at once a peculiar 

 tissue and a peculiar organ. But in the highest organiza- 

 tion, each tissue is found in many organs, and each organ 

 consists of many tissues. Muscle, nerve, and bone, for 



1 P. 107. 



2 If I understand Dr. Beale, he believes rapidly-growing morbid'growths, 

 of the cancerous tj'pe, to lie caused by cellular growth being in such excess 

 as to destroy the power of development. (See Beale's edition of Todd and 

 Bowman's Physiology, pp. 92, 130.) It is known that cancer consists of 

 "fungous" cellular tissue of very low organization. It is very interesting, 

 and to my mind satisfactory, thus to find this most fearful of all classes 

 of disease traceable, like commoner diseases, to a distm-bance in the balance, 

 or harmonious action, of the different vital functions. 



