342 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1921. 



The germ would be a microcosm containing all the different colloids 

 of the adult organism; if the experiment of Guyer and Smith is 

 valid, I do not see how we can escape that conclusion. It contains, 

 moreover, nothing contradictory to the Mendelian conception, for 

 the chemical determinant or the representative colloid can very well 

 be homologous with the Mendelian factor. In fact, Guyer and 

 Smith show that the germinal element affected by the crystallolysin 

 acts very nearly like a recessive Mendelian factor. When males or 

 females with abnormal eyes are crossed with healthy individuals, not 

 treated, coming from other regions, the progeny always appear with 

 normal eyes (dominance) ; but the young are heterozygotes and con- 

 tain in a dominated state the defective eye character, for if these 

 individuals of normal appearance are crossed with rabbits with 

 defective eyes, there appears this time among their progeny a more 

 or less large number of young with abnormal eyes. Two individuals 

 with defective eyes (dominated homozygotes) , bred together, should 

 produce according to the hypothesis of a simple and typical 

 Mendelian factor, only young presenting the anomaly. If it is not 

 always so, there is at least a striking majority with opaque or 

 reduced lenses among their progeny. The evidence is still insufficient 

 to see clearly into the genetics of the character, but in the main, 

 leaving out of the question details which will probably be cleared 

 up later, the characters normal-eye and lysis-eye form an allelo- 

 morphic pair with dominance of the former. 



Can it be said that the experiment of Guyer and Smith is entirely 

 satisfactory ? Far from it ; an evil fate decrees that the proofs of the 

 heredity of acquired characters never present that completeness of 

 evidence which irresistibly entails conviction and leaves the mind 

 at rest. Crystallolysin has a truly disconcerting action; it does not 

 act on the lenses of the pregnant mother, a first anomaly, which, it 

 is true, has received a more or less good explanation; it acts ca- 

 priciously on the crystallines in course of development of the fetuses 

 (9 times in 61), and according to the hypothesis, on the crystallinian 

 determinants of the germinal cells of the same fetuses. We should 

 then expect that it would also affect the germinal cells in the ovaries 

 of the mother, as well as those of the fetuses. But this is not the case. 

 The doe rabbits which survive the injections of anticrystalline serum 

 and which have produced young with abnormal eyes are served 

 several times by the same normal males after the serum treatments 

 have been stopped (for how long a time is not known) and not a 

 trace of ocular malformation is visible in their numerous progeny. 

 There is in that fact something entirely incomprehensible, unless 

 we admit that the female germinal cells can be modified only at a 

 particular stage, that of the period of multiplication of the ovogonia, 



