26 The Ohio Naturalist. [Vol. IV, No. 2, 



long time to explain that phenomenon and it has been revived in a 

 refined, augmented and complex form to stand as the modern 

 theory of light. And so, had selection been advanced at first as 

 an explanation of diversity in plants and animals, it would have 

 meant a far deeper insight into the ways of Nature than the 

 Greeks had at that time. 



What, we may ask, is an acquired character? That it is a 

 difficult task to answer this question one may infer from the fact 

 that in the periodical Nature for 1895, a discussion, ranging over 

 six or seven numbers and led by some of the greatest workers in 

 biology was carried on, each contributor offering a different defi- 

 nition of varying length and complexity. And it is doubtful 

 whether the discussion ended because a conclusion had been 

 reached or whether no more space could be given by the publish- 

 ers. The most comprehensive definition of the term is that an 

 acquired character is a modification of an organism in its ontog- 

 eny, produced by reactions to external stimuli. Its opposite is 

 the congenital character which arises from the genital cell irre- 

 spective of external conditions. Now, obviously, these defini- 

 tions involve severe difficulties, if not in themselves, at least in 

 their application. Fur the sake of clearness, let us consider the 

 development of an organism in ontogeny and phylogeny. 



The Protozoa or Protophyta cannot be said to have an onto- 

 geny. Whatever may be said to be the method of reproduction 

 in them, we ma}^ reduce it to its simplest terms — binar}- fission. 

 Consequently, we cannot speak of palingenesis or cenogenesis in 

 in the protozoa or protophyta. Since there is no division of labor 

 whereby one portion of the organism is set apart to perform the 

 function of nutrition, another for reproduction, etc., we can say 

 that the environment exerts a direct effect on the reproductive 

 element and the transmission of acquired characters in unicellular 

 forms is a reality. But when we pass the line between the uni- 

 cellular forms and multicellular forms, our problem is different. 

 Here we have division of labor. One cell has as its special func- 

 tion the elimination of waste; another, movement, while the thirtl 

 reproduces the animal or plant in its entirety. The question 

 arises, is the method here the same as in the unicellular forms ? 

 Or is there a modification necessary to meet the new conditions? 

 In the case of the one celled forms, the nivirouii/e>if of the repro- 

 ductive element is the environment of the organism as a whole, 

 while in the multicellular forms the environment of the germinal 

 cell is the group of cells surrounding it — \.\\^ environment of the nuil- 

 ticellular organism being the medium outside the body which 

 rarel)' or never comes in contact with the germ cell, at least until 

 that cell is mature. Hence the ca.se is different. In the latter 

 case — i. e , the nnilticellular organisms, the generative cell would 

 react to such stinnili as are furnished by the surrounding body. 



