ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 449 



Effect of Light on Rod-visual Cells of Frog.* — L. B. Arcy exposed 

 Rana pipiens to bright diffuse light for eight hours, and to total darkness 

 for twenty-eight hours. The myoid of the red rod- visual cell elongates 

 in light and shortens in darkness. The mean length of 1000 myoids from 

 twenty-three light-adapted eyes was 11-6 /x; that of 1000 myoids from 

 twenty-three darkness-adapted eyes was .5 • 9 /x. The myoids of the green 

 rod-visual cells are considered to show the same changes, but in a less 

 degree. 



Melanophores of Fundulus.f — R. A. Spaeth finds that the melano- 

 phores of this killifish respond to electrical stimulation after the fashion 

 of smooth muscle, and are to be regarded as transformed smooth muscle- 

 cells. 



c. General, 



Colour Mutations in Mice.| — F. B. Sumner reports on the occur- 

 rence of some rather striking " sports," which seem to behave as dis- 

 continuous hereditary variations. Thus partial albinism occurred in 

 hybrids between the sub-species Peromyscus mankulatus sonoriensis and 

 F. maniculatus ruUclus. Peculiar " yellows " appeared in a race of 

 P. maniculatus gambeli. Various peculiarities in marking are also noted. 



Poison-glands of Snakes. §— Marie Phisalix finds that the poison- 

 gland so strongly developed in proteroglyphous Colubrida3 and in 

 Viperidse has its homologue in the parotid gland of opisthoglyphous 

 and aglyphous Colubridae. This parotid gland was found in seventy- 

 two opisthoglyphous and aglyphous species out of ninety-five examined ; 

 so that it must be called frequent rather than constant. Further exami- 

 nation showed the occurrence of a parotid in various representatives of 

 Boidae and related families (Ilysiids, Uropeltidte, Xenopeltidae, Ambly- 

 cephalidse). The relation of the gland to the dentition was also studied. 

 There are species without parotids which have, nevertheless, fangs 

 {Prosymna, Pseudaspis, etc.) ; there are species with parotids but with- 

 out fangs {Coronella, Contia, Xenopeltls) ; some members of a genus may 

 have a parotid while others have not {Coluber, Polyodontophis, Rhadlnea, 

 Leftognathus, etc.) The presence or absence of a parotid gland is 

 independent of the dentition in snakes derived from Boid^e. Further 

 experiments are required to show whether the parotid is to be regarded 

 as essentially and primarily venomous, or whether it is primarily a 

 salivary gland which has secondarily taken on a venomous function. 



Ornamentation in Killifishes.|| — Henry W. Fowler discusses some 

 features of ornamentation in killifishes, or toothed minnows (Fundulinse). 

 During the spawning season there are in some species minute spinules 



* Jouru. Comp. Neurol., xxvi. (1916) pp. 429-42. See Physiol. Abstracts, i. 

 (1916) No. 8, p. 350. 



t Amer. Oourn. PKysiol., xli. (1916) pp. 577-602. 

 + Genetics, ii. (1917j pp. 291-300. 

 § Comptes Eeudus, clxiv. (1917) pp. 959-62. 

 II Amer. Nat., 1. (1916) pp. 743-50 (10 figs.). 



Oct. mil, 1917 2 H 



