Varietäten etc. — Physiologie. 277 



segregating progeny from the few seeds of a sterile plant as also 

 in the progeny of heterozygotic fertile plants; but there could in 

 some families also be found an excess of recessives (steriles) in the 

 offspring of these plants. In the present investigation therefore, not 

 only the occurrence of a dominant allelomorph in the corresponding 

 recessive homozygote was observed, but also the transformation of 

 allelomorphs in the opposite direction, that is, the transformation 

 of the dominant allelomorph into the recessive allelomorph. The 

 probable frequency of these allelomorphic transformations may be 

 practically constant in a certain strain, and possibly may be different 

 in different strains. As to the conditions under which such allelo- 

 morphic transformations take place, nothing is yet certain except 

 that these conditions are of a hereditary nature. 



M. J. Sirks (Wageningen), 



Troland, L. T., Biological enigmas and the theory of 

 enzyme actio n. (American Naturalist. LI. p. 321—350. 1917.) 



It is the writers conviction that the conception of enzyme 

 action, or of specific catalysis, provides a definite, general Solution 

 for all of the fundamental biological enigmas: the mysteries of the 

 origin of living matter, of the source of variations, of the mechanism 

 of heredity and ontogeny, and of general organic regulation. In 

 this conception he believes we can find a Single, synthetic answer 

 to many, if not all, of the broad, outstanding problems of theoretical 

 biology. It is an answer moreover, which links these great biological 

 phenomena directly with molecular physics, and perfects the unity 

 not only of biology, but of the whole system of physical science, 

 by suggesting that what we call life is fundamentally a product of 

 catalytic laws acting in colloidal Systems of matter throughout the 

 long periods of geologic time. This view implies no absurd attempt 

 to reduce every dement of vital activity to enzyme action, but it 

 does involve a reference of all such activity to some enzyme action, 

 however distantly removed from present activity in time or Space, 

 as a necessary first cause. Catalysis is essentially a determinative 

 relationship, and the enzyme theory of life, as a general biological 

 hypothesis, would claim that all intra-vital or hereditary determi- 

 nation is, in the last analysis, catalytic. The paper gives an extensive 

 exposure of these the writers views about enzymes as biological 

 factors, with many quotations from other authors on chemistry and 

 biology. M.J. Sirks (VVageningen). 



Weatherwax, P., The evolution of maize. (Bull. Torrey Bot. 

 Club. XLV. p. 309-342. f. 1—36. Aug. 1918.) 



"Vestigial organs being considered, Zea, Euchlaena and Trip- 

 sacum are identical in structural plan. The present aspect of each 

 is due to the suppression of some parts which were present in a 

 primitive ancestor having perfect fiowers borne in one type of in- 



florescence Zea, Euchlaena and Tripsacum have descended 



independently from a common ancestral form now extinct." 



Trelease. 



MacDougal, D. T. and H. A. Spoehr. The origination of 

 xerophytism. (Plant World. XXI. p. 245—249. (Oct. 1918). 1919.) 



The conclusions reached are, in the words of the authors "that 



