ZOOLOGY AND BOTANY, MICROSCOPY, KTC. 455 



selections, that selection on the basis of personal somatic qualities only, 

 as such, in and of itself, has altered hereditary factors in the germ-plasm. 

 This view makes selection a cause of genetic variation, a total reversal 

 of the position held by Darwin and most of his followers. The opposing 

 view is that selection can only be successful in altering the type when 

 heredity determiners to produce the desired somatic qualities are already 

 present in the germ-plasm. Selection, on this view, has nothing what- 

 ever to do with the causation of the variation, and is wholly powerless 

 and without effect on the race, unless either {a) the basis of tlae selection 

 is directly gametic, by means of progeny performance test, or (&) the 

 somatically selected individuals happen by good fortune to carry the 

 necessary hereditary determiners in their germ-plasm." 



Digital Malformation.* — A. Clerc and Bobrie describe in an Arab 

 tirailleur — without any pathological feature, or trace of rachitism, or of 

 glandular insufficiency — an interesting malformation of the digits as 

 revealed by radiographs. The fingers were very unequal. The second 

 phalanx of the little finger was a small cubical body ; the second phalanx 

 of the second finger was divided into two ; the first finger of the left hand 

 showed in its second phalanx the -separation of a small rounded bone 

 from the main portion. In the toes the second phalanx was absent on 

 the little toe, reduced to a small body on the fourth and third. On the 

 second toe the second phalanx was formed of two pieces side by side, 

 producing a somewhat bifid appearance. The two feet were symmetrical 

 with one another, which was not quite true of the hands. There may 

 have been some partial ossification of phalanges and subsequent separa- 

 tion of bony parts, which were united by cartilaginous bridges. 



Changes in Skin with Age.f — Ed. Retterer finds that in youth 

 and adult life the dermis is renewed at the expense of epithelial cells 

 of the epidermis. In advanced age the epithelial ceils proliferate less or 

 not at all. The epidermis becomes more delicate ; it no longer gives 

 over any cellular element to the dermis ; it contributes to the atrophy 

 of the dermis. The diminished vitality of the epidermic cell is the cause 

 of the atrophic or senile condition of the skin. Thus Retterer confirms 

 his previous conclusion that the epithelium contains a reserve of living 

 matter, and may be regarded as a persistently formative tissue. 



INVERTEBRATA. 



MoUusca. 



New England Molluscs. | — Charles W. Johnson has made a faunal 

 list of New Zealand molluscs, which contain 738 species and 71 varieties. 



* C.R. Soc. Biol. Paris, Ixzs. (1917) pp. 123-6 (4 figs.), 

 t C.R. Soc. Biol. Paris., Ixxix. (1916) p. 1113-8. 



X Occasional Papers Boston Soc. Nat. Hist., vii. No. 18 (1915, received 1917) 

 pp. 1-231. 



