112 REPORT 1864. 



for food are attended with far more inconvenience and misery to the 

 creatures thus destroyed than obtains, in the majority of cases, where 

 animals are sacrificed on the altar of science ; for, in the latter case, not 

 only are the experimental animals generally destroyed suddenly, but, in 

 those instances where the act of life-departure is more prolonged, the 

 employment of anaesthetics is frequently made use of. Believing, however, 

 that it is not necessary to offer any further apology in favour of the experi- 

 mental methods commonly adopted in our biological inquiries, I now proceed 

 to notice the several species of Entozoa which have been made the subject 

 of investigation. 



1. Tcenia ecJiinococcus. — Of all the mischievous parasites known to infest 

 the human body, none are capable of producing such dire resiolts as those 

 affected by the larvae of this very minute tapeworm. I will merely add, 

 that it is not only the cause of the formidable Echinococcus-endemic in 

 Iceland, but that it also in this country destroys many persons annually. 



On the 30th September, 1862, I fed a house-dog with several hundred 

 Echinococcus-heads (scolices), obtained from the body of a youug person 

 who had been destroyed by this parasite. On the 28th of November of the 

 same year I killed the dog, but could discover no trace of the Tcenice to which 

 these larvae are believed to be referable. 



On the 14th January, 1863, I administered five small Echinococcus- 

 vesicles to a dog which ate them greedily. Similar administrations were 

 also made on the 2-J:th of the same month, and again on the 6th of February. 

 To the results likely to be obtained from these experiments I looked forward 

 with considerable interest ; but, on the evening previous to the day I had 

 appointed for the dog's destruction, some person liberated the animal. 

 Should the experiments in this case happen to have been successful, the 

 freedom of the dog could only serve to spread abroad the very formidable 

 disease which it is the object of these experiments to check. Those, there- 

 fore, who are hostile to our researches should bear in mind that interference 

 with our pursuits may be attended with results seriously affecting the welfare 

 of the community. 



On the 2nd of February, 1863, I fed another dog with several Echino- 

 coccus-vesicles taken from the lungs of a sheep ; and, on the 6th of the 

 same month, I repeated the dose with veiy fresh cysts. On the 25th 

 of February I also destroyed this dog, but found no examples of the cha- 

 racteristic Tcenio'. The animal would not have been destroyed thus early, 

 only I feared losing it altogether from the cause above mentioned. 



On the 6th of February, 1863, I gave about fifty Echinococcus-scolices to 

 a puppy. This animal was destroyed on the 10th of March, 1863; but, so 

 far as the Echinococci were concerned, the result was entirely negative. 



On the 28th of March, 1863, I administered to another dog scrapings 

 from the interior of a large Echinococcus-cyst, which, associated with several 

 other vesicles, had caused the death of a second person. The first patient 

 came under the medical care of Dr. Greenhow, while this case belonged to 

 Dr. Murchison. On the 9th of AprU following the animal was destroyed ; 

 but I had not succeeded in rearing the Tcenia ecJiinococcus. Had the para- 

 sites been present in this or any other of the dogs thus carefully examined, I 

 am confident they would not have escaped my notice, especially since the 

 possession of specimens of the adiilt tapeworm kindly sent me by Professor 

 Leuckart, of Giessen, had rendered me familiar with its characters. 



2. Tcenia serrata. — This well-known species infests the dog in its adult 

 stage, the larvae being, beyond all dispute, the well-known pea-shaped 



