208 GENETICS [BoT. Absts., Vol. IX, 



that all buds in 1 chain of Polychaete Myrianida are of the same sex, and that male- producing 

 and female-producing stocks are alike in structure and behavior. These stocks, however, 

 are different in certain biological features. Thus, male-producing stock buds more freely, 

 since 10-30 individuals are found in one male chain, rarely more than 5 in one female chain. 

 Also, male-producing stock is slender, its tissues transparent, its nephridia indistinct like 

 those of a young worm, while female-producing stock is stouter, and its tissues dense and 

 opaque like those of the old animal. At the beginning of sexual reproduction (March) male 

 chains are rare and female chains rather common, and there are many fragile specimens not 

 yet budding. Non-budding individuals decrease and male chains increase in number as the 

 season advances, until male chains are the more abundant. As autumn approaches, however, 

 female chains are in the majority. Male chains collected in this latter period have fewer 

 individuals and male-producing stocks are stouter than earlier in the season. As a male- 

 producing Myrianida ages it approaches the condition of female-producing stock, acquiring 

 a degree of intersexuality; that is, in a sense, it is a protandrous hermaphrodite. Changes 

 are related to activity of metabolism, a high rate being associated with male-production, a 

 lower rate with female-production. — A, Franklin Shull. 



1321. Dembowski, Jan. Das Kontinuitatsprinzip und seine Bedeutung in der Biologie. 

 [The principle of continuity and its significance in biology.] Vortr. u. Aufsatze Entwicklungs- 

 mech. Org. 21: 1-132. 1919. — In evolution, characters do not arise singly and successively; 

 the whole organism is altered simultaneously. Neither evolution nor ontogeny can occur 

 under constant conditions. Definitions of heredity involving parent and offspring are mis- 

 leading, since heredity is a process and is continuous. Germ-plasm is the basis of conti- 

 nuity, but Weism Ann's theory employing a system of discrete objects violates the principle of 

 continuity. The whole organism is composed of germ-plasm. Germ cells hold no indepen- 

 dent place in the organism ; there is no fundamental distinction between soma and germ-plasm, 

 and no distinction between inherent and acquired characters. The capacities of living sub- 

 stance have no beginning, they simply exist. The development of any animal rests upon one 

 phenomenon, namely, continuity of living substance with all its capacities and properties. 

 The gene is not a unit of heredity, but a unit of development ; the organism does not consist of 

 such units, Mendelians merely recognize them. Progress in heredity will be made only when 

 causes of phenomena are discovered, and such discoveries will come, not from hybridization 

 experiments, but from study of general physico-chemical processes in ontogenetic develop- 

 ment. Form in embryogeny is the result of the physico-chemical constitution; it is never a 

 cause, being itself the effect of properties of living substance. Individuality of chromosomes 

 is not proved by constancy of number, nor by constant size differences, nor by constant diff- 

 erences of form; and other e\^idences of individuality are of doubtful or negative value. 

 Reduction division is asserted to result in all possible combinations of chromosomes, hence 

 chromosomes must be equal, otherwise abnormalities would occur. The structures in the 

 nucleus have no greater influence on development than do yolk and oil droplets. Facts 

 supposed to show the importance of chromosomes may be otherwise explained. Chromosome 

 theories of heredity have no significance. To find the material of heredity the chemistry of 

 protoplasm must be studied. A developing embryo is a single continuous thing, its division 

 into cells is of no significance. A formless, little-differentiated living substance, or plasma, 

 is responsible for the course of development. The fate of blastomeres depends on their 

 chemical and physical composition and that of their surroundings. Gastrulation is a physical 

 phenomenon. The course of regeneration depends upon undifferentiated plasma, and the 

 problem of regeneration is much like the problem of ontogeny, for germ-cells are not predes- 

 tined elements but owe their capacities to their origin from plasma not involved in ontogeny. 

 Regeneration is not a function of cells at the wound, but of the entire continuous organism, 

 for cells at the wound would not, apart from the remainder of the whole, regenerate what they 

 do. The principle of continuity harmonizes the contradictions of vitalism. It shows, for 

 example, that an echinoderm egg is neither a machine nor a harmonious equipotential system. 

 The statement of the vitalist that biology is an independent fundamental science violates 

 the principle of continuity because it confuses phenomena with the method of investigation. — 

 A. Franklin Shull. 



