XII] 



COCKROACH 



239 



the crop and there true digestion is effected. The digested and 

 dissolved food then passes through the filter of the gizzard into the 

 mesenteron, where absorption of the nutritious parts is effected, 

 the undigested portions passing on to the intestine and so out of the 

 body. The cells of the mesenteron undoubtedly exert some action 

 on the products they absorb, though we are ignorant of its pre- 

 cise nature, but in the end they pass on the products of digestion 



.-.17 



18 



FIG. 99. A Female Cockroach, Stylopyga, with the dorsal exoskeleton removed 

 and dissected to show the viscera. Magnified about 2. 



1. Head. 2. Labrum. 3. Antenna cut short. 4. Eye. 5. Crop. 

 6. Nervous system of crop. 7. Gizzard. 8. Hepatic caeca. 9. Mid-gut 

 or mesenteron. 10. Malpighian tubules. 11. Colon. 12. Kecturn. 

 13. Salivary glands. 14. Salivary receptacle. 15. Brain. 



16. Ventral nerve-cord with ganglia. 17. Ovary. 18. Spermatheca. 

 19. Oviduct. 20. Genital pouch in which the egg-cocoon is found. 

 21. Colleterial glands. 22. Anal cercus. 



altered no doubt to the blood which everywhere bathes the 

 alimentary canal, and by it the new material is conveyed all over the 

 body. 



The blood is kept in circulation by the heart which lies in 

 the mid-dorsal line close under the skin ; in fact it can be seen 

 through the skin in the region of the abdomen. It is a long vessel 

 made up of thirteen chambers corresponding with the three thoracic 



