242 SOME OBSERVATIONS ON NEMATOIDEA IMPERFECTA. 



rior is covered with an epithelial layer, the cells of which are granular, apparently contain- 

 ing oil granules, and measure 1.4200th of an inch in diameter. The posterior extremity of 

 the ventriculus is rounded, and usually contains a large, oblong, translucent, highly refractive 

 mass, of viscid oleo-albuminoid fluid, with several smaller globular masses of the same 

 matter. When the worm is submitted to pressure, a portion of this matter exudes from 

 the anus, with a number of transparent nucleolar and nuclear bodies, but the termination 

 of the ventriculus, or its connexion with the anal aperture is indistinct. 



The anus is a short oblique fissure, passing inwards and forwards, upon the ventral sur- 

 face, a short distance in advance of the posterior extremity of the body. It is bounded 

 by projecting lips, but its communication with the intestinal canal I could not detect. 

 Posterior to the ventriculus, the body is occupied with a fluid, finely granular, and a 

 coarsely granular oil-like matter. The remainder of the intervals of the body is filled with 

 fluid and faintly granular matter. 



Measurements. — Length, 1 to 2 lines; breadth at mouth, t. 600th in.; breadth at commencement of ventricu- 

 lus, 1.280th in.; greatest breadth, about middle, 1.150th in.; breadth just in advance of anus, 1.250th in.; length 

 of caudal spine, 1.2500th in.; from base of spine to anus, 1.300th in.; breadth of ventriculus at commencement, 

 1.320th in.; breadth of ventriculus at middle, 1.214th in.; breadth of ventriculus at termination, 1.280th in. 



This entozoon I have seen in hundreds of the Passahis, at all seasons of the year, but 

 in none did I ever discover it in any other stage of development than the one just described. 



From the frequency and great numbers in which it is found, I thought it would afford 

 an excellent opportunity to try the experiment, if upon introduction into another animal 

 it would undergo any progress in its development. I accordingly obtained from the forests 

 in our neighbourhood, and through my friend Baird, from the forests near Carlisle, over 

 200 individuals of Passalus Camillas. A dozen of them I opened, and found them all 

 infested with great numbers of the entozoon just described, and I therefore naturally con- 

 cluded from this fact, in addition to past experience, that most, or probably all the other 

 insects contained the same. Having obtained a dozen large frogs, (Rana pipiens,) after 

 keeping them two weeks until they had voided all indigesta from the alimentary canal, 1 

 killed 8 of them, and examined them closely for entozoa. In seven, I found in the lungs 

 Dis/omum variegation ; in all, Dislomum cygnokles in the bladder; none in the intestines; 

 and in five, an imperfect stage of a species of Filaria beneath the mucous coat of the 

 stomach, in the mesentery, and in the abdominal muscles. 



The remaining four frogs I then fed daily upon 10 individuals of Passalus cormdus each, 

 for four days in succession, so that each frog in that time took 40 insects, — in all, 

 160. It is not to be presumed that the frogs voluntarily took this prescribed fare, for I 

 was under the necessity of cutting off" the legs, elytra, and mouth organs of the insects, 

 and then forcing them into the throat of the frogs. 



In twenty-four hours after taking the first involuntary dose of insect food, the frogs 

 commenced voiding the indigestible pergamentaceous segments of the skeleton of the in- 

 sects per anum, which they continued for a week after the unusual mode of administer- 

 ing their food was stopped. 



At the end of two weeks from the commencement of feeding the frop;s I killed one of 

 them, and carefully examined the intestinal canal and other organs for the Neniatoideum 



