INFUSORIA AS PARASITES. 
301 
terminal flagellum, may be conveniently relegated to the order 
of the Cilio-Flagellata, and is notable for its association with 
the human subject. Unlike the various forms so far enu- 
merated, it is not, however, an inhabitant of the intestinal 
viscera of its selected host, but attaches itself to the passages 
pertaining to the respiratory system, being, according to its 
discoverer, an active agent in the production of one form of 
the infection known as 4 Hay asthma’ or 4 Hay -fever.’ The 
sputa, and mucous matter discharged from the throat and 
nasal passages of patients suffering from this ailment, were in 
every instance found to contain living examples of this 
animalcule, while they were entirely absent in the instances 
where the health was not so affected. The inhalation of 
dilute carbolic acid, or quinine, together with the direct 
application of the first-named medium, was found to yield 
immediate relief, and after a few days’ perseverance in 
its application, to effect a complete and permanent cure. 
A microscopic examination of the mucous discharge after 
the application of either of the above-named remedies revealed 
the presence of the animalcules in a dead state only, thus 
affording additional evidence of their intimate connection with 
the irritation diagnostic of this somewhat remarkable ailment. 
While it would seem certain that the organism now under 
discussion represented the active principle in the cases 
investigated by Dr. Salisbury, it would not seem to apply 
in all instances. A form of Bacteria has been reported 
to exert a similar influence, its growth and irritating pro- 
perties being checked by like remedies ; while with many 
constitutions all the distressing symptoms of hay-fever are 
apparently produced through the mere contact of grass-pollen 
with the mucous membrane of the nasal passages. 
Proceeding to an enumeration of the very considerable 
number of types belonging to the Ciliate section of the Infu- 
soria that are characterized by their parasitic habits, the first 
and by far the most important place has to be allotted to the 
family group distinguished by the title of the Opalinidse, every 
representative of which is, without exception, endoparasitic in 
some member or another of the vertebrate or invertebrate divi- 
sions of the animal kingdom. This essential and invariable 
endoparasitic mode of existence, combined with the circum- 
stance that all the numerous generic and specific types are 
distinguished by the entire absence of an oral aperture or of 
the capacity of in any way ingesting solid food particles, has 
influenced many biologists to regard the Opalinidse as a group 
of organisms entirely distinct from all the four orders of 
the Ciliata as now recognized, and by some, even, as an in- 
dependent animal group, having no affinity with the Infusoria, 
