SPONGES 89 
The way once opened,a number of other writers 
have followed in announcing new discoveries in regard to 
the growth of the sarcode, fiber etc. 
For some years after this discovery, sponges were re- 
tained among the Infusoria, but about 1870 European 
writers upon sponges began to consider them as rather 
higher in rank,andappeared to be inclined to place them in 
a separate division. In 1875, Prof. A. Hyatt, as mentioned 
in the introduction, -issued his Revision of the North Amer- 
ican Poriferae, in the second part of which he says “Since 
these Memoirs were begun, my views with regard to the 
affinities of the Sponge have changed completely, so that 
instead of regarding them as a class of Infusoria, I now 
look upon them as a distinct sub-kingdom or branch of an- 
imals, equivalent structually to the vertebrata, or any of the 
larger divisions which are characterized by the most impor- 
tant structural differences.” | 
Hackel, a German, in 1872, published a Monograph of 
of the Calcareous Sponges in which he lays special stress 
upon the fact that all sponges in common with inverte- 
