198 LEISURE-TIME STUDIES. 



have died from the trichina-disease induced by his own act. 

 Nor may the fatality of the trichina disease be regarded as a 

 mystery in the light of the facts as to the numbers of the 

 parasites which one " host " may contain. Dr. Cobbold 

 affirms, and with good reason, that 20,000,000 of trichinae 

 may be contained in one subject. In one ounce of muscle 

 taken from a cat which had been experimented upon as a 

 producer of trichinae, Leuckart estimated that 325,000 of the 

 parasites were contained. An average-sized man, weighing 

 ten stones, will carry about four stones of muscle ; and 

 assuming that all the voluntary muscles of the body were 

 affected, such a person might afford lodgment to 30,000,000 

 of these parasites. In this instance, therefore, numbers 

 clearly mean power, and that, too, of a fatal kind. 



The history of the trichina's development again brings 

 before us a most singular series of phases, and once more 

 presents us with the necessity for a "double-host," as in 

 the case of the tapeworms. If we start with the trichina 

 as they exist within the muscles of the pig, we find that the 

 parasites are contained each within the little sac or cyst 

 already mentioned. The pig, it may be remarked, is not 

 the only host which affords lodgment to the trichina, since 

 dogs and cats, rats and mice, rabbits and hares, oxen, horses, 

 sheep, guinea-pigs, and other animals, are found to be sub- 

 ject to their attack. It must, however, be noted that, as 

 found in the muscles of any animal, the trichinae are not 

 only perfectly harmless to that animal, but, further, exist in 

 an undeveloped or immature condition. As seen enclosed 

 in their' little sac-like cradles (Fig. 23), the trichinae are, in 

 every sense of the term, "juvenile" parasites. They re- 

 present, in fact, a young and rising generation waiting for a 

 favourable turn of Fortune's wheel to start them on the 

 further stages of their life-history. This favourable turn 

 arrives at the moment when the flesh containing the young 

 and immature trichina-population is eaten by a warm- 

 blooded animal. Suppose the " trichinaised " flesh of a 

 pig to be eaten, without due culinary preparation, by man, 



