ZOOLOCiY AND ItOlAMY. MlUKOSGOl'Y, KJ'U. 387 



b. Histolog-y. 



Eye of Alligator. — H. Laurens and S. R. Detwiler {Jouni. 

 Exper. ZooL, 1921, 32, 207-34, 13 figs.). The eye of Alligator 

 })u'!<sissippiensis has cMvell-developed tapetuiii in the dorsal and posterior 

 portions of the retina, formed by inclusion of guanin in cells of the 

 epithelial layer. The pecten is a slightly raised pigmented cap covering 

 the entrance of the optic nerve. Typical rods and cones occur through- 

 out the retina — one type of rods, two types of cones. The actual change 

 in position of the pigment in the visual cells between eyes in light and 

 in darkness is slight, but when combined with the change in the length 

 of the visual cells gives an effective migration equal to the sum of 

 the two. ' J. A. T. 



Retina of Phrynosome. — S. R. Detwiler and Henry Laurens 

 {Journ. Compar. Neurol., 1920, 32, 347-56, G figs.}. The general 

 structure of the retina of Phrijnosoma cornutum bears a close resem- 

 blance to that of the chameleon. There is a prominently developed 

 area centralis in the form of a circular convexity above the point of 

 entrance of the optic nerve, with a maximally developed fovea at its 

 centre. K highly vascular conical pecten projects dorso-anteriorly about 

 1 m.m. into the posterior chaml)er of the eye. I'he retina possesses 

 only cones, resembling in this respect other diurnal sanrians. The 

 cones exhibit a considerable variety in size, shape, and structure. The 

 cones of the fovea are greatly attenuated and cylindrical in form as 

 compared w'ith the conical form in the extia-foveal region. No double 

 cones were seen. The pigment under ordinary conditions of illumina- 

 tion extends down over the visual cells, almost to the paraboloids, except 

 in the foveal region, where only the outer segments are covered. 



J. A. T. 



c. General. 



Changes in Intensity of Oxidation. — W. E. Burge and E. L. 

 BurCtE {Journ. Exper. ZooL, 1!)21, 32, 203-6). The low rate of 

 oxidation in the unfertilized ovum (potato- beetle) is attributed to its 

 low catalase content. The increased oxidation in the fertilized ovum, 

 with resulting development, is attributed to an increase in catalase 

 l)rought about by the stimulation of the egg to an augmented produc- 

 tion of this enzyme by the spermatozoon. Similarly, the increase in 

 the respiratory metabolism or oxidation in youth and the decrease in old 

 age is attributed to the increase in catalase in the young animal, and its 

 decrease in the aged. J. A. T. 



Eye-muscles of Eagle-Owl. — M. Bartels and CI. Dennler (Zool. 

 Anzeiger, 1020, 52, 49-55, 3 figs.). Although the eye of the eagle- 

 owl is not known to move during life, and cannot be moved after death, 

 the usually six muscles are present. There are two strong muscles 

 which draw the nictitating membrane downwards over the immobile 

 eye. J. A. T. 



Recent Advances in Parasitology. — Ernest Carroll Faust 

 {Trans. Amer. Micr. Soc, 1921, 40, 75-8S). An interesting review 



