ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 539 



Hypermely in the Frog* — 0. Bender has studied a case of a super- 

 numerary hind leg in the frog. He gives a full description of the 

 skeletal parts and the musculature, and discusses the question of origin. 

 He supposes that at a very early stage some unknown agency divided 

 the blastema of the appendages into unequal parts, the smaller of which, 

 not containing a full complement of parts, developed into a defective 

 extra limb. 



Origin of Supernumerary Limbs.f — Ludwig v. Mehely describes an 

 interesting case of a toad (Pelobates fuscus) with three fore-limbs on 

 the left side, one the original member, a second the super-regenerated 

 left, and a third the corresponding right. In this hexapod animal there 

 were three shoulder-girdles on the left side — three pre-coracoids, three 

 •coracoids, three scapulae, and a minute description of the maze of bones 

 is given. The cause was doubtless a wound, and from each wound- 

 surface a regeneration of the peripheral parts has gone on. The author 

 discusses the general question of regeneration. It is necessary to re- 

 cognise the physiological unity of parts like appendages, but it is not 

 necessary to postulate any teleological principle. 



Cell Communications between Blastomeres.f — Cresswell Sheurer 

 describes delicate intercellular strands connecting one blastomere with 

 another in the developing ova of the Serpulid Eupomatus and in the 

 gastrula of Polygordius. He discusses similar cell communications which 

 other investigators have recorded. Our conception of the cell-theory 

 needs some remodelling, as Sedgwick, Whitman, and Meyer have pointed 

 out. In the words of Sachs, cells are " merely one of the numerous 

 expressions of the formative forces which reside in all matter." 



Behaviour of Vertebrate Spermatozoa in Solutions.§ — H. Adolphi 

 has investigated the behaviour of spermatozoa of various mammals, birds, 

 amphibians, and fishes, with particular reference to currents. In the 

 ■case of mammals, for eiample, in salt solution where there is no current 

 they swim in straight lines in all directions, getting up a speed of about 

 40 ft per second. Against a stream of 100 /* per second they fought 

 hard but were carried back. In streams of from 10 /a to 17 fx they 

 swam against the current with a speed of 33 /i to 25 /j. per second. A 

 stream of 5 /x has no directing influence. Similar results in general 

 were obtained for birds. It is suggested that the pressing forward of 

 the spermatozoa to the tube funnel of the oviduct is due to this 

 peculiarity of going against the stream. Frogs' spermatozoa, however, 

 also swim against the stream, a fact which can have no significance for 

 fertilisation. In fishes, the sperms of most individuals as far as investi- 

 gated appear to swim in circles. The decided swimming against the 

 stream evident in mammals is quite absent in fishes. 



Factors Determining Growth and Activity of Mammary Glands. || 

 J. E. Lane-Claypon and E. H. Starling have made experiments which 



* Morph. Jahrb., xxxv. (1906) pp. 395-412 (1 pi.). 



t Math. Nat. Ber. Ungarn, xx. (1905) pp. 239-59 (9 figs.). 



% Proc. Roy. Soc, Series B, lxxvii., No. B 520 (1906) pp. 498-505 (1 pi.). 



§ Anat. Anzeig., xxviii. (1906) pp. 138-49 (2 figs.). 



I Proc. Roy. Soc, Series B, lxxvii. No. B520 (1906), pp. 505-22 (1 pi.). 



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