NATURE'S INSURGENT SON 35 



not been recorded as occurring in this country. It is 

 not at all improbable that this disease is also in truth 

 one which only occurs in the trail of Man. It is quite 

 likely that the artificial conditions of sewage and gar- 

 bage set up by Man on the sea-coast are responsible for 

 the prevalence of this parasite, and the weakly recep- 

 tivity of the too numerous sand-hoppers. 



It is probable enough that, from time to time, under 

 the influence of certain changes of climate and asso- 

 ciated fauna and flora due to meteoric or geologic 

 movements parasitic disease has for a time ravaged 

 this or that species newly exposed to it ; but the final 

 result is one of the alternatives, extinction or adjust- 

 ment, death or toleration. The disease does not estab- 

 lish itself as a scourge against which the diseased 

 organism incessantly contends. It either obliterates its 

 victim or settles down with it into relations of reciprocal 

 toleration. 



Man does not admit this alternative either for him- 

 self or for the domesticated and cultivated organisms 

 which he protects. He ' treats ' disease, he staves off 

 'the adjustment by death,' and thus accumulates vast 



gave a further account of this organism, and named it Bacillus Giardi 

 after Professor Giard of Paris. (Bulletins scientifiques de la France 

 et de la Belgique, xxi. 1898, p. 144). 



It appears that the parasite is transmitted from one individual to 

 another in coition. The specimens studied by Giard and Billet were 

 obtained at Wimereux near Boulogne. I found the disease very abund- 

 ant at Ouistreham near Caen in the summer of 1900. I have not 

 observed it nor heard of its occurrence on the English coast. Sea- 

 water commonly contains a free-living phosphorescent bacterium which 

 can be cultivated in flasks of liquid food so as to give rich growths which 

 glow like a lamp when the flask is agitated so as to expose the contents 

 to oxidation. This bacterium is not, however, the cause of the ' phos- 

 phorescence ' of the sea often seen on our coasts. That is due in most 

 cases to a much larger organism, as big iis a small pin's head, and 

 known as Noctiluca miliafis. 



D 2 



