22 



1 i/A7.7r.i.v M('si':(.\i or \.\rri:M. nisroin 



first coniplclc treatise in t his depaii- 

 ni( lit , and the l)ase lor all In it her work. 



A coinph'te re\'ohitioii in tlie theory 

 and i)racti('e ol" medicine has heen 

 l)roU<>,ht al)oiit tlirou<;h t he ajjpheation 

 ol hioh)<»,i('al knowh'dj^e. 'i'he stiuhes 

 of I.ouis Past(nir upon yeast and its 

 life were the l)e|;innin<i;s ol l>acteri()- 

 l()ji;y and protozoolojiiy, which deal \vi!h 

 theniinuteorganisHiscausinji; numerous 

 diseases of man and of lower animals. 

 What ])iolojj;ists liavo discovered about 

 the causes of malaria, yellow fever, 

 siiiall pox, and a host of other malaches 

 iias done more to alleviate human 

 suffering than all of the researches 

 made prior to the time of Pasteur. 



Since Darwin's time, the all-inclusive 

 doctrine of evolution has become better 

 und(^rstood and more clearly form- 

 ulated, especially as regards the central 

 process of heredity. For a long time 

 after tlu^ ' H)rigin of Species" appeared, 

 the main question in dispute was con- 

 cerned with the supposed inheritance 

 of modifications ac(|uire(l during the 

 lifetime of an individual. Spencer was 

 the chi(^f representative of those who 

 adopted thf^ Lamarckian dictum that 

 such was the procedure in the trans- 

 formations of successive generations. 

 Those who upheld Darwinism con- 

 tended that only the congenital factors 

 were effective, and that the transmis- 

 sion of individually acquired charac- 

 ters was unhkely on a priori grounds. 

 The work of many mvestigators on tlu^ 

 minute structure of the cell, and es]:)(H*i- 

 ally that of Weismann in thc^ last 

 decade of the tree's life, provided 

 definite evidence that there was a con- 

 crete physical basis of heredity which 

 followed such a course during the life- 

 time of an individual and in the pro- 

 duction of offspring as to render the 



bainarckian interpretation untenable. 

 In the nuclei of all cells including the 

 germinal elements is the deeply-stain- 

 ing substance called cJirotnatin, wiiich 

 is (leri\cd ecjuall}' from the two 

 l)arental germs, and which is trans- 

 mitted during the course of develo])- 

 ment to the germ-cells from which 

 the offs[)ring of the next generation 

 arise, in a continuous and uninter- 

 rui)te(l course. 'J'he chromatin bears 

 the hereditary Tiualities of the species, 

 in a way that is unknown in all of its 

 details, but the fact remains that it 

 does. Even the varied qualities of 

 sex can be assigned to a specific num- 

 ber of the chromatin bodies. The 

 results of breeding experiments with 

 plants and animals, like those obtained 

 even in Darwin's time by the monk, 

 Gregor Mendel in the obscurity of his 

 Austrian monastery garden, are in 

 entire accord with the fundamental 

 tenets of Weismannism. in brief, 

 such facts and many others lead in- 

 evitably to the conclusion that the 

 essential things in inheritance and in 

 evolution are the congenital qualities, 

 and that the environment has only a 

 limited value in a quantative way. 



The whole doctrine of evolution, and 

 its principal statement relating to 

 heredity, are extremely important for 

 all those subjects which are founded 

 upon the study of the nature and 

 biological relations of organisms, in- 

 cluding man. Every department of 

 human thought and life, social, relig- 

 ious, intellectual and industrial, has 

 been profoundly influenced and modi- 

 fied by the marvelous discoveries of 

 science which have occurred even 

 since this Sequoia attained gigantic 

 ])r()])ortions. 



What progress, material as well as 



