The Rut in Sheep. 



51 



interrupted now and then by a jerking action — thereby giving 

 evidence of their being ciliated bodies ; but the object-glasses 

 then at our command were insufficient in magnifying power to 

 bring the cilia into view. After this time, more and more of the 

 ova parted with their opercula, and always with a proportionate 

 increase in the number of circular-shaped embryos. Judging 

 from the developing process as seen to be going on in the 

 interior of an ovum from the first gathering together of the yelk 

 to the formation of cells, we reckoned that five or six embryos 

 were yielded by each ovum. 



In a short time numerous infusoria — polygastric monads — 

 existed in the fluid, which were slow in their movements, devoid 

 of colour, and in several respects similar to the Monas enchelis 

 of Pritchard. Whether these infusoria owed their presence to 

 an alteration of the original circular-shaped embryos of the 

 fluke into the ovoid form of the monad, we could not at the 

 time satisfactorily determine ; but subsequent researches would 

 lead to this conclusion. 



Throughout the entire year of 1854 a gradual increase of 

 detached opercula took place, but at its close, and even down to 

 April 15, 1855, when our observations were discontinued, a 

 very large number of the ova were as perfect in appearance as 

 when originally placed in the water. Circular-shaped embryos, 

 and flattened, flask-shaped monads were still very abundant, 

 but no higher form of animal life could be detected. 



We have given the particulars of this experiment, because 

 everything which tends to create thought is of importance in 

 studying the natural history of the liver-fluke, and of material 

 use in helping to explain many of the phenomena connected 

 with an outbreak of rot. 



Several analogous instances of the long preservation of the 

 germs of future entozoa within the egg, even under supposed dis- 

 advantageous circumstances, can be adduced. Ktichenmeister, in 

 describing the treatment for Ascarides, says : " The first thing 

 to be done by the surgeon in practice consists in the destroying 

 the eggs of the Ascarides whenever he meets with them, and 

 exterminating every female that he can get at. It was H. E. 

 Richter's merit that he first ascertained that the eggs remain 

 uninjured in sewage, &c. Recently Barry, Bischoff, and others 

 have proved that the process of segmentation of the eggs of 

 Nematoida continues even in very concentrated alkalies or salts. 

 According to tin? experiments of Verloren and Richter, already 

 described, the eggs of Ascarides only attain their lull maturitj 

 when free in nature (in water), and only undergo tin 1 process of 

 segmentation in this situation. In the various species of Ascarides 

 the time necessary for this purpose may he different ; for whilst, 



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