UNICITY OF BACTERIOPHAGE PROTOBE 359 



it is the theory which is defective. The theory, not the facts, must be 

 modified. Such a state of affairs is not new; it has occurred many times 

 in the history of science. 



We must leave aside the virtually insoluble question of the first cause 

 of life, but we may discover something about the source of this first 

 cause, for there are only two possible hypotheses. It may result from a 

 special organization, a cellular organization; or it may be derived from 

 a particular state of protein matter. In the first case the smallest 

 possible particle of living matter is the cell, in the second, it is the micella. 



Up to the present, dominated by histologists whose conception stops 

 precisely at the limit of visibility with the microscope,* and whose 

 reasoning is this — -"all living beings that we see are cellular, consequently 

 life results from a cellular organization," — the first hypothesis has been 

 generally adopted. Submission to this dictum of visibility is not, how- 

 ever, quite uniform, for certain independent minds whose opinion carries 

 great weight, Beijerinck for example, have repudiated this concept 

 absolutely. 



The two experimental facts bearing upon the bacteriophage corpuscle 

 are unquaHfiedly in contradiction with this a priori hypothesis. But, 

 as we have said, when hypothesis and experimental facts contradict 

 one another it is the hypothesis which must yield to the facts. Just as 

 soon as experiment shows that a corpuscle, constituted of a simple 

 protein micella, is a living being, it follows that life does not require a 

 cellular organization; that it results from a special physico-chemical 

 state of matter, that is, the protein micella. 



From the philosophical point of view, this fact is the most important 

 one of the many which have been revealed through the study of the 

 bacteriophage. 



Up to the present time the infravisible agents of rabies, of variola, 

 of vaccinia, of encephahtis lethargica, of the animal plagues, and of the 

 mosaics of plants, have been considered by the majority of biologists 

 as living beings, but this point of view has been, however, disputed. 

 Although the proof of the hving nature of the bacteriophage is only 

 vafid for itself alone, it is none the less true that the hving nature of all 



* Happily, physicists have succeeded in divorcing themselves from the idea of 

 vision, which always leads to error, as the history of science abundantly proves. 

 If they had studied the nature of matter with the mental concept of the histolo- 

 gists the electron would yet remain to be discovered. I hasten to add that many 

 of the most eminent histologists are beginning to take exception to this point of 

 view; they are abandoning their science for physical chemistry. 



