1887.] NEW-YORK MICROSCOPICAL SOCIETY. 51 



NOTES ON THE ROACH (BLATTA ORIENTALIS, L.). 



BY F. W. LEGGETT. 

 {Read June 3J, 1887.) 



I. Respiration. 



Under the first microscope I have a living specimen, and 

 under the other the stigmata and tracheae of the Blatta orienta- 

 lis. This aristocratic insect can boast a pure lineage reaching 

 back to, if not beyond the coal measures. 



The part to which I desire to call attention is the breathing 

 process. Of this Huxley says, " There are ten stigmata on each 

 side of the body, eight in the abdomen and two in the thorax. 

 The latter are situated between the prothorax and the meso- 

 thorax, the mesothorax and the metathorax respectively, above 

 the attachment of the coxae, and beneath the terga. The ab- 

 dominal stigmata lie in the soft integument which connects the 

 sterna and terga of the somites. All the stigmata are situated 

 in conical thickened elevations of the integument. The tho- 

 racic stigma are the largest, and the anterior pair have a dis- 

 tinctly two-lipped aperture, the anterior lip being notched in 

 the centre. The openings of the abdominal stigmata are more 

 oval, and are inclined backward. Immediately within each 

 stigma the tracheal trunk into which it opens is provided with 

 a valvular arrangement, by which the passage can be closed or 

 opened. The large tracheae which take their origin from these 

 stigmata immediately divide and give off dorsal and ventral 

 branches ; the former unite in a series of arches on each side of 

 the heart, while, on the ventral side, the branches are connected 

 by trunks which run parallel with the abdominal ganglia." 



Huxley is less explicit in his description of the breathing ap- 

 paratus, than of other parts of the Roach, and fails to notice 

 the bellows-like motion of the upper and lower shell of the ani- 

 mal. That this takes place, will, I think, be apparent to anyone 

 looking at the living specimen under the microscope. And the 

 question suggests itself — Is not this the process by which the 

 creature draws in the air, and forces it through the entire sys- 

 tem of the tracheae "^ And again, does this air find inlet and 

 outlet at the same place, or does it enter at the thoracic spira- 

 cles, to be expelled through the abdominal stigmata ? Answers 



