Investigation into the disease of sheep called 'scrapie' (Traberkrankheit: la tremblante) with especial reference to its association with sarcosporidiosis.

  • M'Gowan, J. P.
Date:
1914
Catalogue details

Licence: In copyright

Credit: Investigation into the disease of sheep called 'scrapie' (Traberkrankheit: la tremblante) with especial reference to its association with sarcosporidiosis. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    capsule, too, is brought into evidence by the changes which the sickle undergoes in 1 per cent glucose water, to be afterwards described. Again, if the contents of a ripe cyst are examined fresh, these capsules, now round in shape and empty, can be seen. They are present also in large numbers in the glucose water preparation mentioned above, having extruded their pro- toplasmic contents. As regards the protoplasm of the sickle itself observation leads one to the following views on the subject (see fig. 17a). The number (P) refers to the capsule, and 1 indicates the V- shaped space between the capsule and the protoplasm of the parasite. The sickle has a sharp end and a blunt or nuclear end. The number 4 refers to the nucleus, which remains uncoloured practically when the preparation is treated with dyes. Sur- rounding 4 is a zone indicated by 3, which contains a very large number of chromatic granules, some of fairly large size. Situated nearer the sharp end of the sickle, and apparently definitely differentiated and delimited from zone 3, is a zone 2 which contains no granules. If one examines the contents of a ripe cyst in saline under a high power of the microscope, sickles are observed as just de- scribed, with empty nucleus, a zone indicated by number 3 filled with granules, and zone 2 devoid of them, the whole being surrounded by a capsule. One also sees very numerous small granules about 1 yL6 in size scattered all over the field; empty sickle capsules now rounded in shape; and pieces of vacuolated material, some containing small granules, some emptied of these. Such appearances, though easily found in a fresh prepara- tion in saline, can be much more easily seen by making the emulsion in 1 per cent glucose water and keeping it at room temperature for about three hours. Then one sees that every sickle practically has undergone a change. Fig. 16 gives a rough idea of how this evolution takes place: a ghows a ripe normal sickle; h shows slight enlargement of this; c shows a slight bulge ( fish embryo appearance) on the concave side of the sickle, which is filled with a material containing no granules, at least until the bulge becomes very large. The bulge gets larger, the nuclear spot becomes in- distinguishable, the sickle swells, the granules appear to multiply and get larger, and the protoplasm becomes very