October 4, 1901.] 



SCIENCE. 



521 



b}^ 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 dimen- 

 sions of the vital unit to which he gives 

 the name of biophor may be shortly stated. 

 He takes the diameter of a molecule at 

 g^Q^Q^^ of a millimeter (instead of the 

 one millionth) and he assumes that the 

 biophor contains 1,000 molecules. Sup- 

 pose the biopher 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 



2 00 X lU = xo"oo o"o"o ®^ 2iro"o "0"0 ^'^ ^ 

 millimeter. Two hundred biophors would 

 therefore measure yowoo" ^^ yoW Dana, or 

 1/^ (micron = Y^^oo" mm.). Thus a cube 

 one side of which was 1 /j- 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. 



ISTow if the smallest particle that can be 

 seen (a^owo inm.) may contain 1,250 

 molecules, let us consider how many 

 exist in a biophor, which we may im- 

 agine as a little cube, each side of which 

 is 2Toinro ^^- There would then be 

 five in a row of such molecules, or in 

 the cube 5x5x5 = 125 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 2^y^ of a millimeter. Imagine 

 this a little cube. Taking the diameter of 

 an atom at jo^o^^oo'o' ^^ ^ millimeter, and 

 assuming that about fifty exist in each or- 

 ganic molecule (proteid, etc.), 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 the fecundation of an ovum, has a di- 

 ameter of about Y^-g- mm. Imagine it to be 

 cubed ; it would then contain 25,000,000,- 

 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 as- 

 sume that one-half consists of water, then 

 we may say that the fecundated ovum may 

 contain as many as about 12,000,000,000,- 

 000 organic molecules. Clerk Maxwell's 

 argument that there were too few organic 

 molecules in an ovum to account for the 

 transmission of hereditary peculiarities does 

 not apparently hold good. Instead of the 

 number of organic molecules in the germi- 

 nal vesicle of an ovum numbering some- 

 thing like a million, the fecundated ovum 

 probably contains millions of millions. 

 Thus the imagination can conceive of com- 

 plicated arrangements of these molecules 

 suitable for the development of all the parts 

 of a highly complicated organism, and a suf- 

 ficient number, in my opinion, to satisfy all 

 demands of a theory of heredity. Such a 

 thing as a structureless germ cannot exist. 

 Each germ must contain peculiarities of 

 structure sufficient to account for the evolu- 

 tion of the new being, and the germ must 

 therefore be considered as a material sys- 

 tem. 



Further, the conception of the physicist 

 is that molecules are more or less in a state 

 of movement, and the most advanced think- 

 ers are striving towards a kinetic theory of 

 molecules and of atoms of solid matter 

 which will be as fruitful as the kinetic the- 

 ory of gases. The ultimate elements of 

 bodies are not freely movable each by it- 

 self; the elements are bound together by 

 mutual forces, so that atoms are combined 

 to form molecules. Thus there may be 

 two kinds of motion, atomic and molecular. 



