814 REPORT— 1901. 



are removed by filtration, and if the toxine solution is very much diluted, the 

 solution when injected into a living animal should produce a weaker efl'ect than 

 when the unfiltered fluid is introduced. This, however, is not the case. The 

 filtered fluid, in which no micro-organisms can be seen with the highest powers, 

 after some time, acts as virulently and rapidly as an unfiltered fluid, and the infer- 

 ence is justifiable that invisible micro-organisms are still present, as without these 

 it is difficult to account for the persistence of virulence. I am of opinion, there- 

 fore, that it is quite justifiable to assume that vitality may be associated with 

 such small particles, and that we have by no means reached what may be called 

 the vital unit when we examine either the most minute cell or even the smallest 

 particle of protoplasm that can be seen. This supposition may ultimately be 

 of service in the framing of a theory of vital action. 



Weismann in his ingenious speculations has imagined such a vital unit to 

 which he gives the name of a biophor, and he has even attempted numerical esti- 

 mates. Before giving his figures let us look at the matter in another way. Take 

 the average diameter cf a molecule as the millionth of a millimetre, and the 

 smallest particle visible as the otroTrxr o^ ^ miUimetre. Imagine this small 

 particle to be in the form of a cube. Then there would be in the side of the cube, 

 in a row, fifty such molecules, or in the cube 50 x 50 x 50 = 125,000 molecules. 

 But a molecule of organised matter contains about fifty elementary atoms. So 

 that the 125,000 molecules in groups of about fifty would number ^^g-g^- - 2,500 

 organic particles. Suppose, as was done by Clerk Maxwell, one half to be water ; 

 there would remain 1,250 organic particles. The smallest particle that can be 

 seen by the microscope may thus contain as many as 1,250 molecules of such a 

 substance as a proteid. 



Weismann's estimates as to the dimensions of the vital unit to which he gives 

 the name of biophor may be shortly stated. He takes the diameter of a molecule 

 at ^uijJu (J of a millimetre (instead of the one millionth) and he assumes that the 

 biophor contains 1,000 molecules. Suppose the biophor to be cubical, it would 

 contain ten in a row, or 10 x 10 x 10 = 1,000. Then the diameter of the biophor 

 would be the sum of ten molecules, or j^TyJrTTTju >« 10 = =jTr(5W(TTT ov ^u^'tiUTT oi a 

 millimetre. Two hundred biophors would therefore measure ^innnrT^ o^ ttjVit mm. 

 or 1 fx (micron = x^utt mm.). Thus a cube one side of which was 1 fj, would 

 contain 200 x 200 x 200 = 8,000,000 biophors. A human red blood corpuscle 

 measures about 7"7 fj. ; suppose it to be cubed, it would contain as many as 

 3,652,264,000 biophors. If the biophor had a diameter of xuuuVtjoo ^^- ^^^ 

 number would be much smaller. 



Now if the smallest particle that can be seen C^xjiTytr mm.) may contain 1,250 

 molecules, let us consider how many exist in a biophor, which we may imagine as 

 a little cube, each side of which is i^vvnuT) ™™- There would then be five in a 

 row of such molecules, or in the cube 5x5x5 = 1 25 molecules ; and if the half 

 consisted of water about sixty molecules. 



Let us apply these figures to the minute particles of matter connected with the 

 hereditary transmission of qualities. The diameter of the germinal vesicle of the 

 ovum is ^ oi a, millimetre. Imagine this a little cube. Taking the diameter of 

 an atom at juty^u^tr of ^ mDlimetre, and assuming that about fifty exist in each 

 organic molecule (proteid, &c.), the cube would contain at least 25,000,000,000,000 

 organic molecules. Again, the head of the spermatozoid, which is all that is 

 needed for tlie fecundation of an ovum, has a diameter of about ^ J^ mm. Imagine 

 it to be cubed; it would then contain 25,000,000,000 organic molecules. When 

 the two are fused together, as in fecundation, the ovum starts on its life with over 

 25,000,000,000,000 organic molecules. If we assume that one half consists of water, 

 then we may say that the fecundated ovum may contain as many as about 



that he was using the periods of fatal illness ought to have varied, which they did 

 not do very much. Taking everything into account, while infection by a toxine 

 cannot be absolutely excluded, still in the cases of foot-and-mouth disease and horse- 

 sickness the experiments I think strongly indicate that it is actually some form of 

 life which passes through the filter. 



