62 Dii. WallicHj on the Polycystina. 
also published by that society, I speak with reverence, for 
from the enlarged views pervading the writings of these two 
authors has been gleaned much of the knowledge I have endea- 
voured to turn to account whilst completing a study of organ- 
isms to which, in a living condition, they have not had access. 
'^It is in the structural and physiological condition of 
the animal,^' says Dr. Carpenter, "that we should look for 
the characters on which our primary subdivisions should be 
constituted and in pursuance of this proposition he 
informs us that, notwithstanding " the extreme simplicity and 
apparent vagueness of these conditions, a careful scrutiny 
will make it clear that, under their guidance, lines of demar- 
cation may be drawn as precise as in any other natural group, 
between three well-known types, Amceba, Actinophrys, and 
Gromia ; the sarcode bodies of these three types presenting 
three distinct stages of differentiation of the protoplasmic 
substance of which they are composed, and exhibiting, in 
virtue of that differentiation, three very distinct modes of vital 
activity.^^ (" On the Arrangement of the Rhizopodaj" by 
Dr. Carpenter, ^Natural History Review,^ Oct., 1861, p. 460.) 
The classification based on these three primary types will 
readily be understood on reference to the subjoined table, 
quoted from * The Introduction to the Study of the Forami- 
nifera,' (p. 17). 
Ehizopoda. 
eeticulaeia. 
Gromida. 
PROLOPHYTA. 
Whilst the definitions of the three orders may be advanta- 
geously quoted as given in the abstract already referred to."^ 
* " 1. RETICULARIA. — The body composed of homogeneous granular 
protoplasm, without any distinction into ectosarc and endosarc; neither 
nucleus nor contractile vesicle; pseudopodia composed of the same sub- 
stance as the body, extending and multiplying themselves by minute rami- 
fications, and inosculating comi)letcly wherever they come in contact ; a 
continual circulation of granular particles throughout the viscid substance 
of the body and its extensions. 
*'2. RADIOLAKIA. — Incipient differentiation of the protoplasmic 
substance into endosarc and ectosarc, the former semifluid and granular, the 
latter more tenacious and pellucid ; a nucleus and contractile vesicle ; pseu- 
dopodia rod-like, usually tapering from base to point, composed of same 
substance as the ectosarc, exhibiting little disposition to coalesce or ramify, 
having a more or less regular radiating arrangement, and not showing any 
constant circulation of granules in their substance, although a movement of 
particles adherent to their exterior is often to be distinguished. 
LQBOSA. KADIOLARIA. 
Amoebina. ActinopJiryna. 
Acanthometrina. 
Polycystina. 
Thalassicollina. 
INFUSORIA. GREGARINIDA. | 
SPONGIADA. 
