626 



SCIENCE 



[N. S. Vol. LII. No. 1357 



numerable kinds exist in nature, among wHch 

 relatively a small number has acquired para- 

 sitic or pathogenic qualities. Of the less than 

 p, dozen diseases known or on good grounds 

 .considered to be induced by filterable micro- 

 organisms, two attack human beings, namely 

 poliomyelitis or infantile paralysis, and trench 

 fever; and a third, yellow fever, which until 

 very recently was believed to belong also in 

 this category, has now been relegated to 

 another class, with respect to which special de- 

 vices suffice to bring into view its microbic 

 incitant. 



I There exists, therefore, a degree of uncer- 

 tainty in this field of research for w'hich allow- 

 ance must be made, since it may well happen 

 that suddenly through a fortunate series of 

 experiments or the opening up of new meth- 

 pds, a parasite hitherto regarded as invisible 

 may be brought into microscopic view. 

 Should, for example, complete evidence be 

 brought forward to relate the Rickettsia bod- 

 ies to certain specific infectious diseases trans- 

 piitted especially by insects, as by the wood 

 tick in Rocky Mountain spotted fever, and 

 Jice in trench and typhus fevers, then another 

 group will have been transferred from among 

 the ultramicroscopic to the visible parasites. 

 A similar situation exists regarding the glo- 

 Jjoid bodies of poliomyelitis, the disease of 

 man most convincingly established as induced 

 J)y a filterable microorganism. By means of a 

 highly specialized method of cultivation ap- 

 plicable especially to the class of spiral mi- 

 crobes, or spirochetse. Dr. Noguchi and the 

 ^eaker isolated from the nervous organs of 

 eases of poliomyelitis, globular bodies so minute 

 as to be just at the limit of visibility under 

 the highest power of the .microscope. With 

 cultures of these bodies they induced experi- 

 mental poliomyelitis in the monkey; but the 

 .culture method itself is so intricate that thus 

 ;far few bacteriologists have been able to repeat 

 the work, which therefore still awaits final 

 confirmation. 



Since the recent pandemic of influenza and 

 the assault made upon the so-called influenza 

 bacillus of Pfeiffer, isolated first in Germany 

 during the influenza epidemic of 1889-1890, 



the inciting microbe of that disease has been 

 sought among the filterables. The announce- 

 ,ment of the flnding of such a parasite in the 

 nasopharyngeal secretions by ISTicolle and Le- 

 bailly of Paris in the autiunn of 1918, aroused 

 ;high hopes which subsequent investigations 

 have not served to sustain. The problem was 

 ^approached in a somewhat different manner by 

 itwo workers — Olitsky and Gates, at the Rocke- 

 ifeller Institute. Their studies embraced two 

 ,periods, the epidemics of 1918-1919 and 1920, 

 and the intervening (interepidemic) period, 

 |the latter serving as a control for the former. 

 .The essence of their investigations consisted in 

 iinjecting through the trachea into the lungs of 

 ,rabbits saline nasopharyngeal washings de- 

 irived within the first 24 to 36 hours after the 

 appearance of symptoms from influenza pa- 

 tients and observing the effects (a) upon the 

 ,blood and (&) upon the lungs. The striking 

 changes, in the successful experiments, relate 

 .to the white corpuscles of the circulating blood 

 jWhich suffer a numerical depression affecting 

 .Chiefly the mononuclear type of cells, and to 

 ithe lungs in which multiple hemorrhages and 

 pdema, but not pneiunonia, arise. The effects 

 ,are correlated: where no lung lesions are 

 found no blood alterations occur. These ob- 

 jective phenomena are induced by filtered ma- 

 terials free of all ordinary bacteria (asrobic 

 and anrerobic) and they have not been secured 

 |0therwise than with materials derived from 

 early cases of epidemic influenza; but when 

 present, the rabbits affected very readily be- 

 come subject to the action of various other 

 jbaoteria (streptococci, pneumococci, staphylo- 

 cocci, influenza bacilli), to which they are 

 .otherwise resistant, but which then settle in 

 the lungs and excite fatal pneumonic affec- 

 tions. The unassisted action of the influenzal 

 material is not fatal; only when an ordinary 

 .bacterial lung infection is superadded does 

 ■death follow. All who are familiar with the 

 effects in man of pure influenza and then of 

 influenza complicated with pneumonia of 

 pneumococcal, streptococcal, etc., origin will 

 appreciate this distinction. 

 , What also characterizes the class of diseases 

 incited by the true filterable parasites is their 



