ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 293 



Development of Blood-vessels without Heart— W. B. Chapman 

 {Amer. Jouni. Anat., 101«, 23, 175-203, 17 figs.) finds tliafc in cliick 

 embryos from which the heart has been removed before the establish- 

 ment of the circulation, the emlirjo and area vasculosa remain alive for 

 seven or eight days. There is some growth, and the development of 

 blood-vessels in the area vasculosa is not entirely inhibited. It seems 

 that certain large vessels, such as the sinus terminalis and the anterior 

 vitelline veins, develop as a result of hereditary factors ; self -differentia- 

 tion of the vascular system is very limited ; and the working out of most 

 of the arteries and veins is dependent upon the mechanical factors 

 concerned with the circulation of the blood. J. A. T. 



Vestigial Gill-filaments in Sauropsida.— Edwaed A. Boyden 

 {Amer. Journ. Anat., 1918, 23, 205-35, 4 pis., 3 figs.) calls attention 

 to the formation and relatively late persistence of a band of tissue across 

 the ventral surface of the neck, which is derived from the ventral union 

 of the hyoid arches. From its resemblance to the development of the 

 gill-cover of certain fishes and amphibians it may be called the opercular 

 fold or plica opercular is. On the lateral margins of this operculum, 

 after it has grown backward to enclose at least a potential peribranchial 

 chamber, filamentous outgrowths may be observed on the under side, 

 which in reptiles have a very transitory existence, but in the chick 

 undergo a relatively extensive and prolonged development. On account 

 of the filamentous character of these out-growths, their origin from the 

 branchial arches (the epithelium of which Ekman has shown to possess 

 a certain specificity for gill-formation in the Anura), and their constant 

 relation to the operculum in both reptiles and birds, these structures are 

 adjudged to be true gill-filaments, evidently vestigial in character, but 

 none the less comparable in kind to the functional organs of water- 

 breathing Anamnia. J. A. T. 



Cyclic Variations in Permeability of the Activated Ovum. — 

 Maurice Herlant {C'.R. Soc Biol. Paris, 1018, 81, 151-5) has 

 studied the period of apparent repose between fertilization or activation 

 and cleavage. It is marked in the fertilized egg by the development 

 and regression of the " male " aster and the formation of a bipolar 

 spindle ; in the artificially activated egg by the parallel development of 

 the female aster in the frog, by variations in the volume of the nucleus 

 in the sea-urchin. These are cyclical phenomena, and so are changes in 

 physiological reaction — e.g. susceptibility to various solutions. As R. S. 

 Lillie has suggested, the cyclical changes correspond to changes in the 

 permeability of the cytoplasmic membrane (peripheral zone of protoplasm, 

 not to be confused with the vitelline membrane). Herlant's experi- 

 ments confirm this view. J. A. T. 



Corpus luteum in Ovary of Chicken. — Raymond Pearl and 

 Alice M. Boring {Amer. Journ. Anat., 1918, 23, 1-35, 9 pis., 

 C figs.) demonstrate the homology of the corpus luteum in the hen and 

 the cow. The course of its development in the hen is an abbreviation 

 or fore-shortening of that in the cox. It corresponds directly to the 

 late involution stages of the cow corpus luteum. Both contain a yellow 



