to be properly apprehended. Multiplied observations have now shown that, although very minute, these blood-sucking parasites, if present in large numbers and for a length of time, more especially if its victims are poorly fed, are very dangerous ones indeed. The constant drain of blood which their presence entails, the catarrh arising from the irritation caused by the wounds they inflict on the mucous membrane, the consequent impairment of nutrition, and, possibly, the absorption of some hæmolytic toxin— the product of the parasites— give rise to a grave cachexia, disqualifying to a greater or lesser extent the subject of it for work, and, not infrequently, leading to a fatal issue. It is now recognized that many of the cases which were formerly regarded and diagnosed as " tropical anæmia " are cases of ankylostomiasis.
It is not in every instance in which the ankylostomuin is present that consequences so serious ensue. There may be dozens of ankylostomes in the intestine without any appreciable anæmia, or, indeed, symptoms of any description whatsoever. Grave symptoms are the exception. One must be careful, therefore, to avoid concluding that the ankylostomum is the cause of every pathological condition with which it may chance to concur.
On the other hand, many inhabitants of tropical and sub-tropical countries are in a state of chronic starvation. Living on coarse, bulky, and innutritious food, they are prone to dilatation of the stomach and dyspeptic troubles. In such, any additional cause of malnutrition, as a swarm of ankylostomes, and a daily though perhaps small loss of blood, may be sufficient to turn the scale against them. In those countries, as elsewhere, there are many who live just on the border-land between health and disease; to such the ankylostomum may prove the last straw that breaks the camel's back.
It may be that in some individuals with special susceptibility, some toxin developed by the parasite, just as in certain cases of Dibothriocephalus latus infection, produces a special type of anæmia.
