ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 257 



upon the uterine mucous membrane as soon as it reaches the uterus. 

 It sinks into a small cavity in the uterine wall, and this, the decidua- 

 cavity, is shut off from the lumen of the uterus by a portion of the egg 

 which forms the ectoplacentar cone. Theu the epithelium lining the 

 deciilua-cavity degenerates, and the ectoplaceutar cone gives rise later 

 to the foetal placenta. The point of special importance in the author's 

 results is the absence of epithelium lining the cavity in which the egg 

 lies, which is in direct opposition to the usual view that the decidua- 

 capsule is formed by the growth of a fold of mucous membrane over 

 the egg. 



Development of Acusticofacial and Semilunar Ganglia.* — Dr. K. 

 Weigner has studied this in embryos of pig, souslik (SpermopMlus 

 citilhis), and man. The ganglia in question grow out from the dorsal 

 zone of the medullary region ; no connection with the ectoderm could 

 be established ; the ganglion geniculi separates off from the acustico- 

 facial ; between them a secondary transitory connection was seen at 

 certain stages (in souslik and pig). The cells of the ganglion geniculi 

 are largest ; those of the vestibular ganglion come next ; those of the 

 cochlear ganglion are smallest. They are also distinguishable by stain- 

 ing reactions. 



Epiphysis and Paraphysis in Salamandra atra.f — Prof. H. Blanc 

 finds that the epiphysis developes at the expense of the roof of the mid- 

 brain in the form of a hollow and flattened diverticulum, while the 

 paraphysis arises as a tubular evagination between the fore-brain and 

 the mid-brain. At the outset the two are similar structures made of 

 simple epithelium, but the epiphysis soon undergoes modification de- 

 pendent upon its rapid growth. Its walls thicken and display layers 

 of different kinds of cell, and its lumen becomes filled with cells 

 arranged in cross-bars. From this point the epiphysis displays de- 

 generation. The paraphysis elongates, and its distal surface grows out 

 into a number of hollow buds, while at the same time the adjacent con- 

 nective-tissue, with its numerous capillaries, grows in among these buds, 

 and about the lips of the gaping orifice by which the pai'aphysis opens 

 into the ventricle. In this way the first rudiment of the choroid plexus 

 is laid down, and it developes at the expense of the two lips of the open- 

 ing of the paraphysis. From the course of development, and the histo- 

 logical peculiarities, the author believes that the paraphysis is not a 

 degenerating organ, but is of great importance in connection with the 

 development of the choroid plexus. Like the last-named, it has pro- 

 bably to do with the gaseous interchanges which are carried on in the 

 cavities of the ventricles. 



Two Epiphyses in a Four-Day Chick.J — Dr. Charles Hill demon- 

 strated in 1891 and 1894 the occurrence of two epiphysial vesicles in 

 Teleosts. He notes that others have done the same for Amphibians 

 and Keptiles. In order to see if the duplicity might not occasionally 

 persist in higher Vertebrates, he examined some six hundred chick em- 

 bryos in the fourth day of incubation. Among that number two were 



• Anat. Anzeig., xix. (1901) pp. 145-55 (3 figs.). 



t Arch. Sci. Phys. Nat., x. (1900) pp. 571-2. 



% Bull. Northwestern Univ. Med. School Chicago, 1900, 7 pp. and 6 figs. 



