628 Microscopic Organisms in Blood of Man and Animals, [part hi. 



manifest, that the supposition that beings become asphyxiated as a result of the 

 existence of living organisms in the blood, is untenable. The study of their natural 

 history as they occur in man or animals does not afford the slightest support to such 

 a view. Indeed, so far as we at present know, it would seem that the presence of 

 embryos in the blood, no matter how numerous, exercises no marked deleterious effect 

 on the organism. It is probable, however, that the parents of these organisms, 

 especially when helminthic, do exert a deleterious influence on the well-being of 

 their hosts, — as, for example, the lesions which exist in the walls of the blood-vessels 

 caused by the Filaria saTigwinohnta, would seem to indicate. With regard to allied 

 conditions in man, it is to be inferred that the influence exerted by nematoid 

 embryos in inducing disease is apt to be overrated, as it would seem that the parasites 

 may sojourn for long periods in the system without inflicting obvious injury. That 

 certain injuries are effected, however, cannot well be doubted, but judging from what 

 we know of the like condition in animals, the injuries result, not from direct action 

 of living organisms on the blood-current in which they dwell, but from their action 

 on some of the delicate tissues through which the blood circulates — such injurious 

 influence being probably exerted more especially during the migrations of the parents 

 of future embryo-hsematozoa. 



As it cannot be said that the vegetable organisms which may be found in the 

 blood undergo any such transformations, the injury which their presence is supposed 

 to occasion must be due tx) some other influence. What this may be it is difficult to 

 conceive : the ordinary explanation that they consume the oxygen which is required by 

 the blood itself cannot be regarded as sufficient. 



Calcutta, 

 August 1878. 



ADDENDUM. 



Since the foregoing was written it has been found practicable to furnish facsimile 

 reproductions of a few of the micro-photographs referred to in the text. They have 

 - been reproduced as permanent photographs by the Autotype Company. 



