INSECTS 



finest matter consists of great quantities of minute grains 

 (d) floating about separately or adhering in irregular 

 masses. Besides these elements there are many droplets 

 of oil (e), recognizable by their smooth spherical outlines 

 and golden-brown color. The fat cells are mostly irregu- 

 larly ovoid or elliptical in shape; their protoplasm is filled 

 with large and small oil globules, and contains also masses 

 of fine granules like those floating free in the blood. These 

 granules are the protoplasmic substances formed within the 

 fat cells. Many of the cells have irregular or broken out- 

 lines (b, c), as if their outer walls had been partly dis- 

 solved, and the contents of such cells appear to be escap- 

 ing from them. In fact, many are clearly in a state of dis- 

 solution, discharging both their oil globules and their pro- 

 teid inclusions into the blood; and it is clear that the 

 similar matter scattered so profusely through the blood 

 liquid has come from fat cells that have already disin- 

 tegrated. All these materials will gradually be consumed 

 in the building of the tissues of the adult, the organs of 

 which are now in process of formation. 



In Chapter IV we learned that every animal consists of 

 a body, or soma, formed of cells that are differentiated 

 from the germ cells usually at an early stage of develop- 

 ment. The function of the soma is to give the germ 

 cells the best chance of accomplishing their purpose. An 

 insect that goes through two active forms during its life, a 

 larval and an adult form, differs from other animals in 

 having a double soma. The entire organism, of course, is 

 not double, for, as we have just seen in the study of the 

 caterpillar, many of the more vital organs are continuous 

 from the larva to the adult; but there is a group of organs 

 which, after reaching a definite form of development in 

 the larval stage, at the end of this stage virtually die and 

 go into dissolution, while a new set of tissues develops 

 into new organs or into new tissues replacing those that 

 have been lost. The groups of somatic cells thatform the 

 tissues and organs that undergo a metamorphosis, there- 



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