No.1.] BUDDING [N GOODSIRIA AND PEROPHORA. 203 
with the greatest ease and certainty; the difficulty is found in 
ascertaining the source of the ganglion. On the other hand, as 
we shall presently see, in Perophora the origin of the ganglion 
from the common Anlage is seen with perfect distinctness, 
while the source of this common Anlage is ascertained with 
considerable difficulty. 
It is a suggestive fact that in Pervophora the difficulty en- 
countered in making out the origin of the ganglio-hypophyseal 
Anlage is precisely the same as that which we have already 
seen in the way of ascertaining the source of the pericardium. 
In Goodsizta it will be remembered that we found both 
hypophyseal duct and pericardium to arise as_ well-defined 
evaginations from the primitive vesicle. In Perophora, on the 
contrary, we have already seen the pericardium arise, almost 
certainly from the inner vesicle, but, instead of by an evagina- 
tion, by a cell egression so difficult to observe that a trace of 
doubt might be entertained as to whether the cells have in 
reality come from the vesicle or from the surrounding blood, 
or mesenchyme cells. We shall now see the ganglio-hypo- 
physeal Ax/age to arise in the same way as the pericardium, 
and hence in the same way its source is not as absolutely 
beyond question as might be desired. In both genera it 
appears as though the influences which have determined the 
character of the development of one of these structures have 
also determined that of the other. 
Since in Perophora the cloudy point is not the origin of the 
ganglion alone, as in Goodsiria, but of the common Ax/age of 
duct and ganglion, my reference to the four different alleged 
sources of the ganglion, made when treating the development 
of that organ in the latter species, should be recalled here 
and considered in connection with the origin of the ganglio- 
hypophyseal Ax/age. 
The supposition that it originates directly from the nerve 
ganglion of the parent zooid would, in this instance, be so 
obviously unjustifiable that Pizon himself would hardly venture 
to make it. 
In my preliminary I have declared it to be “absolutely 
certain” that the Ax/age does not arise from the ectoderm. 
