1886.] 



MICROSCOPICAL JOURNAL. 



155 



satisfactory description of it the reader 

 must refer to the original, where its 

 peculiar methods of growth are beau- 

 tifully illustrated by colored plates. 



It may not be generally known that 

 in the determination of specific dis- 

 tinctions among bacteria the mode of 

 growth is often quite as characteris- 

 tic of the different forms as the ap- 

 pearance, size, and other features 

 revealed by the microscope. The 

 microscopic appearance of a colony 

 growing upon a slice of potato, on 

 a gelatin plate-culture, or in a tube of 

 gelatin, is often quite characteristic, 

 and enables the experimenter to iso- 

 late the particular species desired for 

 pure cultures when there are colonies 

 of different forms upon one gelatin 

 surface. The bacterirnn of swine- 

 plague, for example, does not liquify 

 the gelatin as it grows, a fact which 

 at once distinguishes it from Bacte- 

 rium tei-mo. 



o 



Life and Death. — The mystery 

 of life is no greater than that of the 

 necessity of death. Go back to the 

 origin of life — as near to it as we 

 ■ can — and we find it manifested in 

 minute particles of matter, which 

 move and grow. They have no visi- 

 ble structure, they only differ from 

 the inert matter around them in the 

 arrangement of their ultimate atoms 

 and molecules. This arrangement, 

 through which vitality becomes pos- 

 sible — which perhaps constitutes life, 

 or all we shall ever know concerning 

 it — when once established under fa- 

 vorable conditions may continue in- 

 definitely. This is true of the sim- 

 plest organisms. A single individual 

 may give rise to an innumerable pro- 

 geny, by indefinitely repeated fis- 

 sion, and though the individual be 

 lost, merged into its unnumliered off- 

 spring, yet its vitality continues. 

 Strictly speaking, among these low 

 forms of life there is no mother or 

 daughter. There is only an original 

 cell that we recognize as an individual, 

 which, by its peculiar power, trans- 

 forms inert matter into bioplasm, and 



the living bioplasm continues this 

 transformation and grows, dividing 

 as it reaches a certain limit of size, 

 and the progeny continue the same 

 operations. 



There is an increase of vital action 

 with growth and the birth of each 

 new cell. An interesting problem 

 for speculation is suggested by this 

 fact. Whence does this increment of 

 vital force come.'' Obviously there 

 must be a transformation of the latent 

 energy of the inert matter that is 

 taken up and foi'med into the bio- 

 plasm. The tearing apart of the 

 atoms of dead matter to form complex 

 organic compounds involves the ex- 

 penditure of enormous energy by the 

 microscopic cell. If we could meas- 

 ure the amount of such work, we 

 could determine the mechanical equiv- 

 alent of the life force. It is not in- 

 credible that this may yet be done. 

 So far as its physical manifestations 

 are concerned, life is essentially a 

 succession of chemical phenomena, 

 in which the atomic forces of inert 

 matter are transformed into their 

 equivalents in the molecules of bio- 

 plasm. Here, as throughout the 

 range of physical phenomena, the 

 law of conservation of energy holds 

 true. The amount of energy in the 

 universe remains constant, but a large 

 proportion of it is constantly under- 

 going change from dead to living, 

 from life to death. As Dr. Minot 

 has inquired, ' May not life be coeval 

 with energy } May it not have always 

 existed ? ' 



o 



Dr. Piersol's Photo-microgra- 

 phy. — The article on photo-microg- 

 raphy by Dr. Piersol, which has 

 already appeared in- these columns, 

 deserves to be carefully read. The 

 use of colored screens in the manner 

 described is not absolutely new, and 

 it has been already mentioned and 

 advised in this Journal, but to Dr. 

 Piersol is due the credit of having 

 made a careful study of the subject 

 as applied to the work upon which 

 he has been engaged, and of perfect- 



