382 SUMMARY OF CURRENT RESEARCHES RELATING TO 



c. General. 



Pigment-formation in Amphibian Larvae.* — Myrtle E. Johnson 

 has found that pigment in tadpoles of Raaa and Hyla is not cor- 

 related with the amount of nutrition, as claimed by Tornier for 

 Pelohates larvae, Ijut, as suggested by instances cited by Darwin and 

 Wallace, is dependent rather upon substances specific for colour in the 

 nutritive material. These substances may bring about a change in 

 the amount of pigment-forming substances produced, or shghtly alter 

 the character or combination of these substances, and thus change the 

 amount or colour of the pigment. Feeding with lecithin checks the 

 pigment-formation to a noticeable degree. It is probable that a tyro- 

 sinase reaction, or a similar oxidase reaction, is the basis of pigment- 

 formation in the tadpole. 



Attachment of Ova in Kurtus gulliveri.t — F. Guitel describes the 

 details of the method of fixation of the eggs in this fish from New 

 Guinea, which has been reported on hj Weber. As Weber showed,, 

 the eggs are fastened in a wreath on a bony hook of the supra-occipital 

 of the male. The females have no trace of the hook, and it does not 

 attain its full size in the male until the breeding season. The hook 

 bends forwards and downwards, and forms a ring or "eye." Through 

 this a round band passes, which is connected with numerous filaments 

 attached to the eggs. From 110 to 140 fine threads pass from each Qgg 

 and form the attaching band. Each filament has a fixed basal portion 

 adherent to the Qgg and a mobile twisted ribbon, the details of which 

 are described. 



It is probable that, as in Cliiius argpMtatvs, the ovarian ovum has 

 layers of filaments twisted around it, and that these uncoil to form the 

 large mass of filaments. 



Influence of Gonads on Sheep. J — F. H. A. Marshall finds that the 

 development of horns in the males of a breed of sheep in which well- 

 marked secondary sexual differentiation occurs (as manifested especially 

 by presence or absence of horns) depends upon a stimulus arising in 

 the testes. This stimulus is essential not merely for the initiation of 

 the horn-growth, but for its continuance, the horns ceasing to grow 

 whenever the testes are removed. The removal of the ovaries from 

 young ewes belonging to such a breed does not lead to the develop- 

 ment of definitely male characters, except possibly in an extremely 

 minor degree. 



Structure of the Fowl's Syrinx. § — A. 0. V. Tymms gives a detailed 

 account of the structure of the syrinx in the common fowl. The fol- 

 lowing points are distinctive. The formation of a syringeal chamber 

 or " tympanum," with extensive membranous walls ; the presence of 

 membranous internal bronchial walls, with the connecting bronchio- 



* Univ. California Publications (Zool.) xi. (1913) pp. 53-88 (1 pi.). 



t Arch. Zool. Exper., lii. (1913) pp. 1-11 (1 pi. and 3 figs.). 



X Proc. R. SocSect. B, Ixxxv. (1912) pp. 27-32. 



§ Proc. R. Soc. Victoria, xxv. ^1913) pp. 286-306 (7 pis.). 



