640 J. T. PATTERSON 
amniotic vesicle. Curiously enough it is found in two or three 
instances that the canals of two embryos unite and enter the vesi- 
cle as a single tube, and in one case at least three canals so unite. 
His figure 2 presents a still more striking case. It contains 9 em- 
bryos, and the embryo lying at the top of the figure, and slightly 
to the right of the center, sends its canal directly to the vesicle, 
while the canals from the four embryos on the right enter the vesi- 
cle very close together, two of them by a common tube. Like- 
wise, the canals from the four embryos lying on the left enter the 
vesicle at a common point. Indeed, they apparently unite just 
before reaching the vesicle. 
In view of the fact that we have shown that the union of two 
canals in T. novemeincta is a certain indication of their common 
origin from a primary bud, I believe we are justified in drawing a 
similar conclusion from the conditions to which we have just 
called attention in T. hybrida. And I venture to predict that 
when Fernandez shall have secured intermediate stages, he will be 
able to confirm this conclusion." 
It does not follow, of course, that in Mulita only two primary 
buds will be found to appear, for while in T. novencincta the poly- 
embryonic process in the ovum is extremely stable, as expressed 
by the constancy with which litters of quadruplets appear, in T. 
hybrida, on the contrary, variability characterizes this process. 
Hence, there are no good reasons why in this species, regions on 
the ectodermal vesicle which correspond to those unoccupied by 
the two primary buds in the vesicle of novemcincta might not 
give rise to new primary diverticula. If this be found to be the 
the case it would in no wise nullify our conclusion regarding the 
origin of polyembryony among the armadillos; that is that it 
began in the ancestors by the formation of twins. Whether all 
of the species which might show such a primitive condition are 
18 After the above was written my attention was called to a report, in the Jour- 
nal of the Royal Microscopical Society, June 1913, page 279, of Fernandez’s commu- 
nication at the Ninth International Congress of Zoologists. From the brief state- 
ment given it seems clear that Fernandez has observed exactly the same method of 
embryo formation in Mulita that I have described for T. novemcincta, that is, the 
embryonic primordia arise as diverticula. He states that the diverticula ‘‘ become 
the primordia of embryos, either directly or after division.’’ (Italics my own). 
