424 THE ANIMAL PARASITES OF MAN 



and jejunum, where they become adult. During this period they do 

 not grow much, the males from 0*8 to ro to 1*2 to 1*5 mm.; the 

 females to 1*5 to r8 mm. Soon after copulation, which takes place 

 in the course of two days, the males die ; the females, which during 

 the following days attain a length of 3 to 3*5 mm., either bore more 

 or less deeply into the villi or, by means of Lieberkiihn's glands, into 

 the mucous membrane (Askanazy, Cerfontaine, Geisse), and thus 

 usually attain the lymph spaces. A few also pierce the intestinal wall 

 and are then found in the mesentery and glands. The females deposit 

 their young, the number of which, according to Leuckart, averages at 

 least 1,500, in the lymph spaces ; the newly born larvae measure 90^ to 

 100 fjb in length, 6 //, in diameter, and they do not appear to increase in 

 size during their migrations. The migrations are mostly passive, that 

 is to say, the larvae are carried along mainly by the lymph stream to 

 the heart, but sometimes they are active, as may be inferred from the 

 fact that young Trichinellae are found in various parts of the intes- 

 tinal wall beyond the chyle and lymph spaces, as well as in abun- 

 dance in the abdominal cavity. Trichinellae occur in the heart's 

 blood of artificially infected animals seven to twenty-three days 

 after infection. If scanty, dilute the blood with about ten times the 

 amount of 3 per cent, acetic acid and centrifugalize. 



The young brood is distributed from the heart throughout the 

 entire body, but the conditions necessary to its further development 

 are found only in striated muscle ; the young Nematodes penetrate 

 the capillaries, attain the intramuscular connective tissue and then 

 invade the fibres (Virchow, Leuckart, Graham 1 ). On the ninth or 

 tenth day after infection the first Trichinellae have reached their 

 destination ; but further invasions are constantly taking place because 

 the intestinal Trichinellae live from five to seven weeks, and continue 

 to produce their young. 



Symptoms. (i) Period of invasion : Gastro-intestinal symptoms 

 nausea, vomiting, watery diarrhoea, colic. Muscular pains may occur 

 even at this period. Recurrent abdominal pains about the eighth day, 

 a temporary oedema. Embryos are abundant in the serous cavities. 



(2) Period of dissemination : Second week. Myositis, variable in 

 amount, is the predominant symptom. The biceps and calf may be 

 hard and tender. Mastication, speech, respiration, etc., may be 

 difficult and painful. Dyspnoea may be intense. Temperature 

 104 to 105 F. 



1 Trichinella; that are unable to penetrate into muscular fibres invariably die, no matter 

 where else they settle ; their occurrence in the adipose tissue is disputed, but is still possibly 

 correct, as bundles of muscles are present in the fat of bacon. The Trichinellse do not settle 

 in heart muscle, although they may reach it in cases of heavy infection ; they then die or 

 wander into the pericardium, and eventually into the heart cavities. 



