Biologie. — Varietäten, Descendenz, Hybriden. 487 



partially isolated from other members of the Community by a high 

 degree of 'homogamy' — like tends to conjugate with like. If this 

 result be confirmed by investigation of other protozoa, the main 

 difticulty feit by Huxlej^ with regard to the „Origin of Species" is 

 in a fair way to Solution, and if Pearl's interpretation be correct, 

 practically b}^ Romanes' „physiological selection". The second fun- 

 damental Problem upon which the measurements throw light is the 

 influence of environment upoa conjugant individuals which to some 

 extent correspond to the germ cells of the metazoa. Pearl shows 

 that environmental conditions are much more pronounced in the 

 case of the non-conjugants than of the conjugants; the latter have 

 far greater relative stability of type. The view of Weis mann that 

 environment in the protozoa produces more directl}- than in the 

 metazoa permanent variations in t3^pe must now be reconsidered 

 from the Standpoint that the protozoa return to a more or less stable 

 conjugant tj^pe. Pearl's investigations naturallj^ lead him to a fuller 

 discussion than has been hitherto attempted of the differentiation in 

 t3^pe, variability and correlation between conjugant and non-conju- 

 gant forms." R. H. Lock. 



Heron, D., On the Inheritance of the Sex-Ratio. (Biometrika. 

 V. 79—85. 1906.) 



Confirms Woods' position on rather wider data in the case of 

 the horse as well as in man; the sex-ratio is found not to be sensibty 

 inherited. R. H. Lock. 



Lock, R. H., On the Inheritance of certain Invisible Cha- 

 racters in Peas {Pisum sativum). (Proc. R. Soc. B. LXXIX, 

 p. 28—34. 1907.) 



The paper deals with certain colour characters of the testa which 

 can be transmitted in an invisible condition b}^ the white or colour- 

 less type, and make their appearance when this is crossed with a 

 coloured t^^pe from which these particular characters are wanting. 

 The characters were 1) small specks of a very deep purple colour, 

 the presence of which may be briefly denoted b}^ the letter p; and 

 2) a mottling or marbling of larger brown patches — m. The grey 

 ground colour upon which these spots appear may be denoted as g, 

 whilst w is the absence of g — a colourless testa associated with 

 white flowers and unpigmented leaf axils. The following view of the 

 inheritance of these characters which was put forward b)' the author 

 in 1904, is shown in the present paper to represent the actual facts. 



m., p., and g. were regarded as each depending on the presence 

 of the dominant member of a separate pair of allelomorphs A — a, 

 B — b, and C — c respectively, C representing the grey ground 

 colour. A and B though present are unable to lead to the appearance 

 of m. and p. in the absence of C. B (p) is totall}" inhibited in this 

 way, whilst the brown marbled character occasionally makes its 

 presence known by the appearance of a kind of faint „water-mark", 

 plants which exhibited this phenomenon being described as „ghost" 

 maples. R. H. Lock, 



MaeDougall, D. T., Hj^bridization of the Oaks. (Botanical 

 Gazette, Reprinted in Scientific American Supplement, LXIII. 

 p. 26105—6. 1 ill., NO. 1629, Mar. 23, 1907.) 



Gives Condensed list of natural hj'-brids of North American 



