180 THE CANADIAN NATURALIST, [June 



meal, suffered more or less from similar symptoms, and in the 

 evening of Thursday called in a physician, who, after careful 

 enquiry, diagnosed Trichin'asis, and called in a second opinion 

 on the case. On Good Friday a slice of ham was submitted to 

 me for microscopic examination, in which I discovered, after 

 some hours' investigation, several characteristic specimens of 

 Trichina spiralis. By Monday morning, with the assistance of 

 my friend Mr Ritchie, I had found several groups of Trichina, 

 both in the free state and partially, as well as fully, encysted. 

 These were during the same day shown to a considerable number 

 of medical friends. 



Mr. C. Baillie kindly placed his micro-photographic apparatus 

 at my disposal, and during the week produced some excellent 

 negatives of the worms " in situ " in the pork muscle. 



No. 1. — This photograph (reproduced by Mr. Inglis) shows a 

 sroup of Trichinae in very close proximity, travelling up a line of 

 muscular tissue, or rather between the muscular bundles. 



No. 4 shows an individual worm surrounded by a gelatinous 

 cyst, protruding his head therefrom, apparently in search of food, 

 for his head and mouth can be distinguished under the 

 microscope in the dark mass of muscle to the right of the field. 

 Above, around and below are the worms not encysted, but 

 curled up in the band of muscle, so that thirteen may be 

 counted on a field of view not exceeding the tenth of an 

 inch in diameter. 



No. 5 shows what appears to be a lateral section of the 

 worm fully encysted, but the worm is really whole, and the 

 section only optical, the cyst being so transparent as to allow 

 focusing through it. The cyst, although perfect, is not 

 calcareous, and in no case did any calcareous cysts present 

 themselves. The above were found in the slice of ham 

 in question, and, indeed, in one particular muscle of that 

 ham, of which the horizontal section did not exceed one- 

 quarter inch in thickness. It is evident, therefore, that the 

 disease was recent in the young pig from which the ham 

 was taken, and that, being in the free and semi-encjsted 

 condition, the worms were in a condition to be aroused into 

 action and activity in a much shorter time than had they 

 been fully and calcareously encysted. According to Virchow^*^ 



» Virchow's archives, 1850, vol. xxxiii, page 535. 



