514 LAW OF VON BAR. 



as, in social undertakings, the division of labor gives greater perfection to 

 the work, so in this, functions which, because they were blended, were 

 imperfectly discharged, now assume precision and power, because they 

 are disentangled from what were perhaps countervailing conditions. 

 By these considerations, we are gradually led to the general law of de- 

 velopment, first recognized by Yon Bar, and passing under 



LawofVonBar. r rrn J ? i 



his name. This is somewhat obscurely enunciated in the 

 following terms : " The heterogeneous arises from the homogeneous by a 

 gradual process of change." By this it is meant that, in the process of 

 development, the stages are not from forms that are of a degraded to those 

 of a higher type, but that from the general the special, which was therein 

 included, is gradually evolved. 



In conclusion of these preliminary remarks on reproduction, it may be 

 Invariable se- ^served that, even in the highest and most elaborate types, 

 quence and dif- the causes which bring on differentiation follow each other in 

 such a predetermined sequence, that the whole phenomenon 

 might be said to be under the dominion of mathematical conditions. As 

 a striking instance of this may be mentioned, in the case of man, the nu- 

 merical equality of the sexes ; and that this singular result is determined 

 by the alternate preponderance of conditions which are otherwise nicely 

 balanced, is shown by the interesting instances occurring among insects 

 of dimidiate and quadrate hermaphroditism, in .the former of which 

 the resulting insect is of different sexes on the .two sides of its body, 

 and in the latter the male and female portions are quadrantally arranged. 

 If the left side of the head and thorax are those of a male- insect, the 

 right half of the abdomen is of the same kind, the intervening portions 

 being of the other sex. The neuter state might even be imagined to 

 arise from the more precise blending, balancing, and confusing of such 

 conditions as here give evidence of an incipient tendency to separate from 

 one another. 



In the farther discussion of reproduction we shall find it conveniently 

 Divisions of considered under two distinct divisions; first, generation; 

 reproduction. secon <3 ? gemmation. Our attention may, then, be profitably 

 directed to the singular facts known under the designation of alternation 

 of generations. As illustrations of the terms here employed, it may be 

 stated that the production of a seed and the development of a plant there- 

 from are to be considered in connection with generation, and that the ob- 

 taining of new plants and trees by budding and grafting, and the pro- 

 duction of many new hydras by their sprouting forth from an old one, 

 are to be considered under gemmation. By the alternation of genera- 

 tions is meant that an organism, A, will give rise to a second one, B, 

 wholly unlike itself, and that this second organism, B, will give rise to a 

 third, C, unlike itself, but C shall resemble A. This singular condition 



