318 



SCIENCE 



[N. S. Vol. XXVUI. No. 714 



of the International Zoological Congress, we 

 have here the difficulty in applying Men- 

 delism that the range of variation of the 

 reicessive character (extra veins) includes, 

 in its somatic manifestation, the lominant 

 characteristic, so that v?hen the recessive 

 character is not well developed we get, 

 even in strains supposedly " pure " with re- 

 spect to the recessive character, flies that 

 somatically lack the extra veins. However, 

 the degree of development of these extra veins 

 is inherited and the study of such inheritance 

 is a typical one of blending inheritance. , 

 Since the degree of development of the ab- 

 normality is inherited there must be a correla- 

 tion between the potency of the " deter- 

 miners " in the germs and the soma from 

 which these germs came, also between them 

 and the soma they produce. Flies having 

 slight abnormalities produce germs tending to 

 have the abnormality-producing factor weak. 

 Wlien such flies are mated with flies which 

 lack the factor the zygote is so weak with 

 respect to the factor that few, if any, of the 

 offspring are abnormal. However, if flies, 

 producing germs strong with respect to the 

 factor, are mated with flies lacking it, ab- 

 normals will be produced. In other words, we 

 have imperfect dominance. This theory of 

 imperfect dominance possesses the advantage, 

 from the Mendelian's view-point, that one does 

 not have to give up a fundamental principle 

 of Mendelism — segregation or purity of the 

 germ. An explanation of certain cases of 

 latency, such as the carrying of pigment pos- 

 sibilities in white animals where albinism is 

 recessive, is also suggested. For example, the 

 spotted condition of guinea-pigs varies in a 

 negative direction until pigment is to be 

 found only in the eyes or in a very small 

 part of the skin,° hence presumably beyond 

 this point, when, although it is germinally 

 present it is not somatically evident. 



In other words, when the ranges of varia- 

 tion of Mendelian pairs overlap, the Mende- 

 lian phenomena will be masked, owing to the 

 inability of the experimenter to properly 

 classify his material. Nevertheless, the 

 fundamental principle of Mendelism — segre- 



' Castle, 1905, Carnegie Pub., No. 23. 



gation — may still be operative. For example. 

 Castle' concluded that the inheritance of poly- 

 dactylism was neither alternative nor blend- 

 ing. May it not be loth alternative and 

 blending ? The distinction seems theoretically 

 important. 



Frank E. Lutz 



distribution of diabase in massachusetts 



No diabase is found west of the Triassic. 

 In the Triassic and east to a line N. 10° E. 

 through the Brookfields is a " Hunne diabase " 

 with two pyroxenes — an augite and a white 

 diopside and feldspars in two generations. 



Next east a series of large dykes runs N. 

 20° E. through Spencer nearly across the 

 state, of a micrographic Hunne diabase, i. e., 

 a rock closely like the above, but containing 

 often abundantly quartz and orthoclase inter- 

 grown. 



The two types repeat the relations of the 

 western bedded diabase and the Palisade dia- 

 base in New Jersey, as recently brought out 

 by Mr. T. Volney Lewis, at the winter meet- 

 ing of the New York Academy of Sciences. 

 Next east in Massachusetts a band of olivine 

 diabase runs north from Blackstone half 

 across the state. 



All the remaining eastern part of the state 

 east of a line drawn about N. 10° W. from 

 the northeast corner of Rhode Island is oc- 

 cupied by a normal diabase, with augite and 

 feldspar in one generation, no olivine or 

 micrographic structure, rich in iron, often 

 showing long rovTS of octahedra; much 

 weathered and running to coarser grain, and 

 in part of pretriassic age. 



Again, in addition to the nepheline rocks 

 around Salem, an interrupted band runs N. 

 10° W. from Woonsocket, near the northeast 

 corner of Ehode Island, across Massachusetts 

 and into New Hampshire, and the olivine 

 diabase mentioned seems to be in relation with 

 the same. These rough notes are presented 

 as a preface to a request that any one having 

 slides of diabase from Massachusetts would 

 kindly send to the writer information as to 

 whether the same contains olivine, diopside, 

 micrographic or porphyritic structure. 



= 1906, Carnegie Pub., No. 49. 



