THE MICROSCOPE 



NOVE^vlBER, 1896. 



Number 47 New Series 



Objects Seen Under the Microscope. 



By chrysanthemum. 



XXXV.— The Cockroach. 



The scientific name of the common kitchen blackbeetle 

 is Periplaneta orientalis; periplaneta meaning to wander, 

 orientalis because of its coming from the east. The 

 cockroach found on ships is Periplaneta americana and 

 it is this that we will study it being- larger than the 

 other although they are very similar in structure. They 

 are nocturnal in their habits, love warmth and shun the 

 light. They are easily killed for study by^ chloroform. 



Structure. — The elongated body is flattened from upper 

 to under surface, and is roughly oval in cross-section. 

 It presents three regions (figs, 1 and 2). Fig. 3 repre- 

 sents the general plan of the typical insect body. The 

 head (fig. 3 c), carrying the jaws and sense organs; the 

 abdomen (g), within which are the most part of the diges- 

 tive, circulatory, respiratory, secretory, nervous and re- 

 productive organs. The head apparently of only one 

 segment, is really of six segments fused together. The 

 thorax is of three segments; the protliorax (fig. 3, d); 

 mesothorax (e); metathorax (f). This external segmen- 

 tation is only repeated internally in the muscles and 

 the nervous system. 



The exterior body is hardened into sclerites. These 

 are cuticular and chitinous, and are thicker, harder and 

 darker brown over the body generally than they are at 

 the joints where the integument is softer and more pale. 



