92 THE POPULAR SCIENCE MONTHLY. 



these suppositions as facts in order to avoid admitting that species of 

 living protoplasm are originated de novo in some fluids just as specks 

 of crystalline matter originate in other fluids, and although some 

 organisms can be seen to make their appearance in fluids independently 

 of all preexisting visible germs, just as crystals do." 



In Part III., Dr. Bastian takes up the processes of heterogenesis, 

 whereby the matter of already existing living units gives birth to 

 other living things, wholly different from themselves, and having no 

 tendency to revert to the parental type. The transformations and 

 developments represented in Figs. 3, 4, and 5, will mainly interest 

 those familiar with the objects delineated, but they are of a very 

 remarkable character. It is alleged that the cells of conferva give 

 rise to euglena, a beautiful green organism which abounds in stagnant 

 water, while this undergoes still further transformation into amceba, 

 and ciliated infusoria. And still more surprising, if possible, is the 

 transformation of the minute algoid chlorococcus into the large, com- 

 plex, and well-known rotifer, Hydatina senta (Fig. 5). 



As Dr. Bastian remarks : " The fact that animals with such distinct 

 and specific organs should arise in this definite manner, from the re- 

 productive products of the plant, will doubtless seem to many to flavor 

 more of fable than of fact." This is undoubtedly true. Dr. Bas- 

 tian's views contravene general experience. The derivation of organ- 

 isms from preexisting germs is the actual method which we know that 

 Nature employs in all grades from the top to the bottom of the scale 

 of life. We know, moreover, that infusorial germs do exist, and float 

 about, in the atmosphere. Besides, all our past knowledge of life 

 implies the slow operation of the forces of evolution. As for the 

 appearance of infusorial organisms in liquids, which a few hours before 

 did not contain them, they must be explained in accordance with 

 known modes of action, until some other method is demonstrated. 

 To this, Dr. Bastian replies 1. That science now admits that, at some 

 period in the earth's history, the lower forms of life have arisen by the 

 operation of natural causes. 2. That all the considerations bearing 

 upon the case favor the view that such organisms may be produced 

 now, and that it is little else than absurd to suppose that " the simplest 

 and most structureless amoeba of the present day can boast a line of 

 ancestors stretching back to such far-remote periods that in comparison 

 with them the primeval men were but as things of yesterday ; " and 

 3. That the de novo origin of living matter, and the transformation 

 of low vegetable organisms into infusoria and animalcula are facts that 

 must now be considered as experimentally established. The whole 

 question will therefore turn on the future testing of these remarkable 

 processes. The subject cannot be allowed to rest here ; and, if Dr. 

 Bastian's experiments shall be verified, the publication of his work will 

 constitute an epoch in the progress of biological science. It may be 

 remarked that the " Beginnings of Life " is written in a popular and 



