SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICEOSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 

 a. Embryology.f 



Mendel's Law of Heredity 4 — W. E. Castle gives a lucid account 

 of the discovery which Gregor Mendel made in 18GG — the discovery of 

 a law of heredity. The law was re-discovered independently in 1900 

 by I)e Vries, Correns, and Tschermak, who were engaged in the study 

 of plant hybrids. It remained, however, for Bateson, two years later, 

 to point out the full importance and the wide applicability of the law. 

 To make the matter clear in a summary, we follow the headings of the 

 analysis which Castle has given. 



(1) The Law of Dominance. — When mating occurs between two 

 animals or plants differing in some character, it often happens that all 

 the offspring exhibit the character of one parent only, and that is 

 called the " dominant " character ; while the character that is not seen 

 in the immediate offspring (though still part of the heritage) is called 

 " recessive.''' When white mice are crossed with grey mice, all the off- 

 spring are grey ; the grey colour is dominant, the white colour recessive. 

 Parents with distinctive characters A and B, yield hybrid offspring with 

 the character A (B) or B (A), the parentheses being used to indicate a 

 recessive character not visible in the individual. This is the law of 

 dominance. 



(2) Peculiar Hybrid Forms. — The law of dominance is not of uni- 

 versal applicability. (1) The cross-bred offspring, e.g. of peas differing 



in height, may be intermediate between the parents (Ax B = -~- ). 



(2) The cross-bred offspring, e.g. of brown-seeded and white-seeded 

 beans, may exhibit what seems to be an intensification of the character 



* The Society arc not intended to be denoted by the editorial " we," and they 

 do not hold themselves responsible for the views of the authors of the papers noted, 

 nor for any claim to novelty or otherwise made by them. The object of this part of 

 the Journal is to present a summary of the papers at actually published, and to 

 describe and illustrate Instruments, Api aratus, etc., which are either new or havo 

 not been previously described in this country. 



f This section includes not only papers relating to Embryology properly so called, 

 but also those dealing with Evolution, Develo] ment, Reproduction, and allied subjects. 



X Pica Amer. Acad., xxxviii. (190!) pp. 535-48. 



