ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 179 



development of the ciliary ganglion, constitutes evidence in favour of 

 the complete segmental character of the nerve too important to be 

 ignored. 



Vascularization Phenomena in Blastoderm Fragments.* — F. P. 

 Reagan has observed the development of fragments (" meroplasts ") of 

 embryonic bodies completely isolated from yolk-sac blastoderm prior to 

 an " invasion " by the so-called yolk-sac " angioblast " (the origin of 

 vascular tissue). After incubation for thirty to forty-eight hours such 

 fragments were found to possess blood-vessels in varying degrees of 

 development. It seems that the embryonic meroplast possesses an 

 inherent capacity for differentiation which tides it over to the time when 

 heart-pulsations would normally provide a means of tissue respiration. 

 As the meroplasts develop legitimate vascular cavities with a good endo- 

 thelium, an augioblastic origin of intra-embryonic endothelium cannot be 

 argued for. The endothelium differentiates from an " indifferent " 

 mesenchyme. The yolk-sac is not necessarily the site of formation of 

 the earliest l:)lood-vessels. Intra-embryonic vessels develop in situ when 

 communication of extra- embryonic vessels with intra-embryonic tissue is 

 prevented by chemical or mechanical means. 



Development of Sound-transmitting Apparatus in Necturus.f — 

 H. D. Reed has re-investigated this much-studied apparatus. It consists 

 of a single plate that accurately fills the somewhat elliptical foramen 

 vestibuli of the mature amphibian, and is connected by a well-defined 

 stilus with the suspensorum of the jaws. But the fenestral plate, 

 though of the single type, is double in origin. The columellar portion 

 is extra-otic, having no early developmental connexion with the ear- 

 capsule. At about the beginning of larval hfe it spreads out over the 

 fenestral membrane, and completely fills the cephalic ■ portion of the 

 fenestra. From this position it gradually narrows, coming to a point 

 and disappearing near the centre of the oval window. The remaining 

 portion, by far the larger, of the fenestra is filled by tissue originating 

 from chondroblasts in the fenestral membrane, and therefore strictly 

 otic. The columellar portion, including the stilus, is the homologue of 

 the columella of Amblystoma. The otic part represents the operculum. 

 The larval characteristics of the plate are shown not in its structure, 

 but in the absence of the musculus opercularis. As a whole, the 

 apparatus in Necturus is morphologically intermediate between that of 

 Amblystoma and that of Plethodontidge. 



Experimental Production of Defective and Monstrous Develop- 

 ment.| — E. I. Werljer subjected eggs of Fundulus to the action of 

 substances like butyric acid and acetone, which occur in the blood or 

 urine of man during metaljolic disorders. A great variety of monsters 

 resulted, analogous and homologous with human and other mammalian 

 monsters. The monstrosities concern the eyes (cyclopia, synophthalmia, 



* Anat. Record, ix. (1915) pp. 329-41 (10 figs.), 

 t Anat. Record, ix. (1915) pp. 581-90 (6 figs.). 

 X Anat. Record, ix. (1915) pp. 529-62 (29 figs.). 



