1882.J 



MICKOSCOPICAL JOURNAL. 



193 



minute particles, agitated by Brown- 

 ian motion, from those of similar size 

 and equal activity really possessing 

 life on their own account. The first 

 may be particles of charcoal finely 

 powdered, or the minute globules of 

 oil in an emulsion ; the second are 

 grouped together under the common 

 name of bacteria. The latter are 

 exceedingly abundant in nature and 

 found in enormous numbers in every 

 putrefying or decaying portion of 

 organic substance, at all times every- 

 where. There is no longer the least 

 doubt, on the part of those who have 

 studied the subject, but that the 

 minute organisms really cause the 

 decompositions and fermentations 

 which have so long been considered 

 spontaneous in all organic matter, as 

 soon as deprived of life. Milk does 

 not turn sour, meat does not putrefy, 

 wood does not rot, a pile of damp 

 vegetable matter does not heat, from 

 any inherent unstableness of their 

 own composition, or from any direct 

 effects of air or temperature. All 

 these things and all others like them 

 are solely due to the operations of 

 the above-mentioned living organ- 

 isms. But from the microscopic ap- 

 pearance alone, one is wholly unable 

 to positively discriminate between 

 some of the not living forms and some 

 others known to be living. For 

 instance, the milk-sap of the Euphor- 

 biae and Chicoraceae swarms with 

 moving atoms when freshly taken 

 from growing plants. Probably these 

 exceedingly minute particles are glo- 

 bules of oily or resinous matter ; but 

 their color, form and motions so 

 simulate the living organisms known 

 as micrococci or microzymes that I 

 question much whether any micro- 

 scopist, from appearances alone, 

 would confidently decide whether 

 they were the one or the other. He 

 would first seek to know where found, 

 what the behavior towards chemical 

 reagents, and what the effects of the 

 consistency of containing fluids, as 

 well as what evidence there was of 

 reproduction and death. 



Knowing that cells have for their 

 exterior a cellulose membrane in 

 which there are absolutely no per- 

 forations large enough to be dis- 

 covered by the highest and best 

 powers of our microscopes, the idea, 

 if it occurred, that parasitic or other 

 living organisms could gain entrance 

 and dwell imprisoned in such manner 

 was stifled under a presumed theo- 

 retical impossibility. This also must 

 have been the case with many other 

 botanists and microscopists, for there 

 is too much evidence to longer 

 doubt that bacteria do sometimes 

 inhabit the cells and tissues of ap- 

 parently healthy plants ! 



As an instance, I noticed in 1873, 

 within the swollen tip of a fertile fila- 

 ment of Ascophora mucedo, a common 

 black mould on bread, decaying 

 fruits, etc., so many rapidly moving 

 particles that in a note made at the 

 time the field of the microscope was 

 said to have the appearance presented 

 by a swarm of gnats in summer air. 

 An explanation was sought at the 

 time in some peculiar activity of the 

 protoplasm of the cell, but examina- 

 tion was carefully made to ascertain 

 whether or not the cell-wall was with 

 or without perforations. For this 

 purpose nothing better could be 

 selected, for the bladdery structure 

 permitted seeing through it in every 

 direction. With a power of about 

 five hundred diameters, no opening 

 of any kind could be discovered, yet 

 I am now very confident that these 

 active atoms were bacteria, and that 

 the motions exhibited were due to 

 their own life forces. How they 

 gained entrance is left solely to con- 

 jecture. 



One year after this a similar note 

 was made in regard to the moving 

 particles observed within the cells of 

 the transparent hairs of a healthy 

 plant of Lophospermum scandetis, a 

 green-house climbing vine. In this 

 case one cell appeared alive with 

 internal motion, while its neighbor, 

 separated only by a thin and quite 

 transparent partition, showed nothing 



