FUNCTIONALLY-CAUSED MODIFICATIONS. 623 



the units at large, then it must happen that such modification must 

 have its effects on all other parts of the organism ; so that there 

 cannot fail to result all those small concomitant variations above 

 indicated. 



May we not also say that it becomes less incomprehensible 

 that structural changes caused by use and disuse are inherited ? 

 If, as we see, a local variation spontaneously arising is accompanied 

 by multitudinous other local variations, implying a necessary 

 correlation between each local variation and the general constitu- 

 tion of the organism ; then it may be argued that if a marked 

 change of function in an organ causes increase or decrease of it, 

 this general correlation implies that there must be a reciprocal re- 

 action between the part and the whole, tending to re-establish 

 their congruity. The constitution at large will in so far be 

 changed, and along with its change will go corresponding changes 

 in the sperm-cells and germ-cells. 



Finally let me add, not another argument, but another fact of 

 observation, of the kind which opponents demand, but which, 

 when they are from time to time furnished, are severally pooh- 

 poohed as not enough. Each of them is spoken of as a solitary 

 fact and slighted as inadequate ; and when by-and-by another is 

 named, this is treated in the same way ; so that the facts which 

 if brought together would be recognized as sufficient are never 

 brought together. That to which I refer is set forth in a pamphlet 

 by M. Leo Errera, Professor at the University of Brussels, 

 entitled " Heredite d'un Caractere acquis chez un Champignon 

 pluricellulaire ; " being an account of experiments of Dr. Hunger, 

 at the Botanical Institute in Brussels. First enumerating various 

 instances of adaptations to climate, as those of plants which, fitted 

 to northern regions, preserve their constitutional rapidity of 

 growth and seeding when brought south, and do this for several 

 generations, he goes on to detail the culture-experiments of 

 M. Hunger, and sums up the results of these in the following 

 words : — 



" On deduit de la que : 



"1° Les conidies d' Aspergillus niger sont adaptees a la concentration du 

 milieu ou a vecu l'individu qui les porte ; cet effet est encore plus marque 

 apres deux generations passees dans un milieu donne (Exper. I et II) ; 



" 2° II s'agit d'une veritable adaptation et non pas simplement d'un 

 accroissement de vigueur chez les conidies provenant des liquides concentres, 

 car ces memes conidies germent moins rapidement et donncnt des plantes 

 moins vigoureuses que les conidies normales lorsqu'on les seme de nouveau 

 sur le milieu-type: en s'adaptant aux liquides concentres, elles se sont 

 desadaptees du liquide normal (Exper. Ill) ; 



" 3° Une generation passee sur le liquide normal n'cfface pas Tinfluence 

 d'une ou de deux generations anterieures passees sur une liquide plus con- 

 centre (Exper. IV). 



"Tous ces resultats concordent: Us monlrent une legdre, mats incontest- 

 able transmission hereditaire de V adaptation au milieu," 



