1038 General Notes. 
his. The area of the chorion frondosum is very small, not over — 
one-fourth of the area of the under side of the placental disk — 
The portion of the chorion underlying the placental disk, but — 
not united with it, belongs to the chorion deve, and its abortive — 
villosities even extend over and are developed on its surface 
somewhat beyond the edge of the placental disk. 5 
The cytoclasts spoken of above are many times the size of — 
any of the rest of the cells found in the uterus, foetus, or foetal — 
membranes, and they also possess very large nuclei. The pro- 
cesses of adjacent cytoclasts spoken of frequently join, and there 
is thus formed a sort of syncytium. This syncytial structure, if 
isolated, would form a ring composed of cytoclasts just at the 
edge of the placenta, and is especially developed at about the 
time the zonary band of mucous membrane around the feetus's 
nearly absorbed. 
These data furnish further proof that the primitive or ancestral 
type of placentation was a more diffuse one than in existing — 
Rodents of the myomorph type, and throws some additional 
light on the manner in which a discoidal type of placentation 
has been derived from one which was zonary.—J. A. Ryder. 
i 
k 
i 
3 
3 
iV 
: 
; 
: 
Z 
a 
7 
f 
PSYCHOLOGY. a 
On Duration of Memory in Wasps.—In studying the ye > 
chology of insects, it is noteworthy that we have very a e “ 
isfactory evidence with regard to duration of memory. sft we | 
=- Observation on leaf-cutting ants, which tends to show recolle ri ie 
of a locality for one year, is by no means conclusive, as the | 
are as well, if not better explained by supposing that tO es | 
__ “Stickney relates a case in which some bees took poe 
- of a hollow place beneath a roof, and having been then rem hé 
into a hive, continued for several years to return and occupy t° 
same hole with their successive swarms.” ded 
ude that bees have i 
as this. 
o Again we quote from Romanes :? ne 
- a ga q his own, showing 
ae 
shut. hen they were again opened in the spring, 
_ returned, although there was no honey in the window. ne 
The : y hat 
e obvious criticism is that we have no evidenc 
4 : Pee 
= * Animal Intelligence, p..154, Prasad : 
