SUMMARY OF CURRENT RESEARCHES 
RELATING TO 
ZOOLOGY AND BOTANY 
(principally invertebrata and cryptogamia), 
MICROSCOPY, Etc. 
Including Original Communications from Fellows and Others .* 
ZOOLOGY. 
VERTEBRATA. 
a. Embryology. f 
Placentation of Perameles.J — M l J. P. Hill has discovered an 
allantoic placenta in Perameles obesula and P. nasuta , and gives a con- 
nected account of the successive stages. 
I. The changes in the uterine wall are briefly the following : — The 
mucosa undergoes hypertrophy ; the uterine glands increase in trans- 
verse diameter and in length ; the interglandular connective tissue forms 
a loose network permeated by lymph ; the vessels of the mucosa increase 
greatly in size and number ; the whole epithelium becomes a vascular 
syncytium ; maternal capillaries pass up between the syncytial lobules 
(formed of nests of nuclei), penetrate the syncytial protoplasm, and form 
a network on and just beneath its surface. 
IT. Fixation of the embryo . The embryo becomes attached to the 
maternal syncytium by means of the enlarged ectoderm cells over the 
discoidal area or true chorion with which the allantois fuses. In cor- 
relation with the close adherence of the chorionic ectoderm, the corre- 
sponding area of the uterine syncytium is markedly thicker than the 
remainder, and forms the allantoic placental area. In the allanto- 
chorionic mesenchyme, and in close relation to the inner surface of the 
chorionic ectoderm, run the allantoic capillaries. 
Outside the discoidal allanto-chorionic area a somewhat annular 
zone of the yolk-sac wall is also brought into intimate relation with 
the maternal syncytium, and represents a yolk-sac placental formation, 
functional at a time when the allantoic placenta is being formed. 
* The Society are not intended to be denoted by the editorial “we,” and they do 
not hold themselves responsible for the views of the authors of the papers noted, 
nor for any claim to novelty or otherwise made by them. The object of this part of 
the Journal is to present a summary of the papers as actually published , and to 
describe and illustrate Instruments, Apparatus, &c., which are either new or have 
not been previously described in this country. 
f This section includes not only papers relating to Embryology properly so called, 
but also those dealing with Evolution, Development, and Reproduction, and allied 
subjects. \ Quart. Journ. Micr. Sci., xl. (1897) pp. 385-416 (5 pis.). 
