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SCIEMCE. 



[Vol. XIX. No. 471 



SCIENCE: 



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LATEST DETMLS CONCERNING THE GERMS OF 

 INFLUENZA. 



Dr. R. Pfeiffer, overseer of the scientifle division of the 

 Institute for Infectious Diseases at Berlin, has the credit of 

 discovering, isolating, describing, and inoculating the germs 

 that are the cause of influenza. The following results are 

 based upon his thorough investigation of thirty-one cases of 

 influenza, in six of which autopsies were made. 



1. In all cases there was in the characteristic, purulent, 

 bronchial secretion a definite kind of bacillus. These rods 

 were shown in uncomplicated cases of influenza, in an abso- 

 lutely pure culture, and for the most part in large numbers. 

 Very frequently they lay in the protoplasma of the pus- 

 cells. Where the patient has been subject to other bronchial 

 troubles, one finds in the sputum, in addition to the influenza 

 bacilli, other micro-organisms. The bacilli can enter from 

 the bronchi into the peri- bronchial tissue, even to the surface 

 of the pleura, where in purulent coats in two autopsies they 

 were found in pure culture. 



2. These rods were found only in influenza. Numerous 

 control-experiments showed their absence in common bron- 

 chial catarrh, pneumonia, and phthisis. 



3. The condition of the bacilli varied with equal force in 

 the course of the disease; first with the exhaustion of the 

 purulent bronchial secretion the bacilli also disappeared. 



4. Two years ago, at the Brst appearance of the influenza, 

 I saw and photographed the same bacilli in large numbers 

 in preparations of sputum from influenza patients. 



5. The influenza bacilli appear as small rods, of about the 

 thickness of septicasmia bacilli in mice, but one-half their 

 length ; frequently three or four bacilli are found arranged 

 one after the other like in a chain ; it is diiBcult to stain 

 them with the basic aniline dyes; one obtains better prepa- 

 rations witli Ziel's solution and with the hot methyline blue 

 of Loffler. In this way one sees almost regularly that the 

 end-poles of the bacilli stain more intensively, so that forms 

 arise which might be very easily mistaken for diplococci or 



streptococci. The bacilli are not stained by Gram's coloring 

 matter; and in banging drops they are immovable. 



6. These bacilli can be obtained in pure cultures; in one 

 and a half per cent sugar-agar the colonies appear the small- 

 est. The continued cultiire in this nutrient medium is diffi- 

 cult, and I have not been able to go beyond the second gen- 

 eration. 



7. Many experiments for transmission to apes, rabbits, 

 guinea-pigs, rats, pigeons, and mice were made. Positive 

 results could be obtained only in apes and rabbits. The 

 other species of animals were refractory to the influenza. 



8. These results .iustify the conclusion that the above de- 

 scribed bacilli are the cause of influenza. 



9. Infection comes very probably from the germs of the 

 disease in the sputum; and therefore for prevention of con- 

 tagion the sputum of influenza patients must be made in- 

 nocuous. 



Dr. Kitasato has succeeded in cultivating the bacilli of 

 influenza to the fifth generation upon glycerine-agar. 



Arthur MacDonald. 



Georgetown Medical School, Washington, B.C. 



A SERIES OF ABNORMAL AILANTHUS LEAFLETS. 



A STURDY trumpet creeper (Tecoma radicans) has en- 

 twined itself about an ailanthus tree which stands in our 

 yard, near the veranda. Together, they form quite a charm- 

 ing bower during the summer time, when the bright trum- 

 pet flowers are so profusely intermingled with the dark green 

 foliage of vine and tree. 



It was here that I had taken my chair one afternoon, to 

 enjoy an hour's undisturbed reading. My anticipations of 

 quiet, however, were very soon interrupted, by a sudden 

 gust of wind, which set the leaves of my book a-fluttering 

 so, that I was obliged to close it. But " it is an ill wind 

 that blows nobody good," I said to myself, as 1 stooped to 

 pick up some leaflets which came fluttering down from the 

 ailanthus tree. 



Although it was only June, these leaflets were of a bright 

 yellow color, like the tints of early autumn. But what at- 

 tracted my attention especially was their variation from the 

 typical form. Every leaflet had a peculiar notch, lobe, or 

 lop-sided outline which would cause it to be classed among 

 monstrosities, or abnormal leaves. These abnormal speci- 

 mens were more to me, however, than mere " freaks of na- 

 ture." They were the tablets on which their own history 

 was inscribed. 



If we take one of the largo ailanthus leaves, with its long 

 rachis and numerous leaflets, we are led to inquire into the 

 manner of its numerical increase of leaflets. At a cursory 

 glance at the leaves we find that although the vast majority 

 are odd-pinnate, there are many which we are scarcely jus- 

 tified in calling odd, nor yet should we denominate them 

 even pinnate. That is, transition stages between odd and 

 even pinnate quite commonly occur, and I would call these 

 "abnormal leaves " transition stages. They are the keys 

 which will unlock for us the mystery of their development. 

 Let us see if such is not the case: let us make use of these 

 keys and thereby learn whether such is not the verdict ren- 

 dered by the leaves themselves. We will put our queries to 

 the terminal leaflets, because they seem to be the centre of 

 evolutionary activity in nearly all pinnate leaves. 



We have quite an advanced transition stage in Fig. 1 of 

 our series; it has quite a conspicuous projection beyond the 

 typical outline on the left side; a prominent vein Is seen ex- 

 tending to the apex of this abnormal projection, from which 



