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REPORT ON ZOOLOGY, MDCCCXLIV.

of the entire mass not being surrounded by any cyst is notopposed to the view of its consisting of Echinococci, because,in rare instances there is no doubt that Echinococci do occurnot encysted. In the second case also an Echinococcus-colony indubitably existed, as is evident from the vesicles ofvarious sizes contained one within the other, and from theprogeny pullulating on their internal surface. But Goodsirshould have described more precisely the ova, which he sayshe saw between the membranes of the vesicular bodies.Just as little does the Reporter dare to express an opinionrespecting the Filarice which Goodsir thinks he observed inthe gelatinous envelop of the vesicular bodies. In the figure,at all events, no Nematoid worm is recognisable ; thecentral granular portion of these filamentous bodies,explained by Goodsir as Filarim, was, perhaps, not black,but colourless, and appeared black by transmitted lightunder the microscope, whilst the same object under re-flected light would have presented a chalk-white colour.In stating the colours of microscopic objects, naturalists havein general paid too little attention to the conditions underwhich the object is regarded, particularly whether by trans-mitted or reflected light.

Goodsir furthermore (Report of the Fourteenth Meetingof the British Association for the Advancement of Science,held at York, 1841. London , 1845 ; Notices, p. 67) ex-presses himself with respect to Entozoa inhabiting cysts,and remarks, quite correctly, that a cyst, the internal sur-face of which secretes a nutrient fluid for its parasites,produces, in time, a substance of too great consistence, inwhich the inhabitants are killed and entombed. But thatGoodsir had still no very clear notion with respect toEchinococcus hominis, is evident from the three species ofCyst-worms instituted by him under the names Acephalo-cystis simplex, monroi, and armatus. The first species issaid to contain only a few young cysts; in the second themother-cyst (germinal membrane) is stated to be subdividedby a fibrous tissue into many compartments, which are