THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



Vol. X. SEPTEMBER, 1889. No. 9. 



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 can Monthly Microscopical Journal, Box 6jo, Washington, D. C. 



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Ova of Trichocephalus Dispar in the Liver of Rat. 



WITH ONE PLATE. 



By EDWARD A. BALLOCH, M. D., 



WASHINGTON, D. C. 



In calling attention to the subject indicated in the title of this paper, 

 I have been guided by the idea that one slide carefully and exhaustively 

 studied is often of more benefit than a more ambitious attempt to cover 

 a larger field at the expense of thoroughness. Keeping this idea in 

 view let us now study the slide before us, which is one that has often 

 afibrded me pleasure and profit. I propose to take it up as if it were 

 not labelled and as if we were studying it for the first time. 



First, then, as to the macroscopic appearances. Holding the slitle to 

 the light we see it to be a section about one-half inch long by one-eighth 

 inch broad, with an outline like the Italian letter " 5'." We also see 

 that it is intersected by numerous fissures and that ditlerent parts of the 

 section have different colors. Now, let us place it on the stage of the 

 microscope and examine it, using first the lower powers. All the 

 naked-eye details are now seen to be intensified. 



The whole section is seen to be bounded by a limiting membrane, 

 prolongations from which also line the numerous fissures. From this 

 we argue that we have to do with a section of a complete organ or 

 structure. But what organ or what structure is it.'' Let us try to de- 

 termine. 



We see that the section is divided into a number of subdivisions of 

 an irregular polygonal shape, some of which are quite distinct, while 

 others seem to be fused with neighboring subdivisions. 



The one marked a (Fig. i) seems to be the most typical. Let us 

 examine it. It is of a pentagonal outline and separated from contigu- 

 ous subdivisions by well-marked fissures. In its centre is seen an open- 

 ing: and with care we are able to make out a delicate lining membrane. 



Copyright, 1889, by C. W. Smiley. 



