PROTOZOA OR SIMPLEST ANIMALS. 7 



Joblot, who, in 1754, first discovered it pirouetting about in an High Wall 

 infusion of celery, speak of it as " the most extraordinary fish one ^^^^ 

 could imagine." A continual streaming of the protoplasm rendered Gallery, 

 visible by the granules in its substance is continually proceeding up 

 and down the psendopods. The little organism reproduces itself by 

 dividing into two (Model -i). 



ActinospJmrium eichornii (see Plate V. in the Case) has a spherical 

 body with a well-defined outer zone of large vacuoles ; this form, 

 which is also abundant in ponds, somewhat resembles a giant Sun 

 Animalcule, being about five times the size of Actinophnjs. 



Rhaphidiophrys eUgam may be either solitary (Model 5), or may 

 form colonies in which several of the spheres are joined by bands 

 (Model (')) ; numerous slender curved spicules of silex abound in 

 the sm-face layer of the body and psendopods. 



Clathrulina ehgans (Fig. 3), which lives in ponds and ditches, 

 may be compared to a Common Sun Animalcule enclosed in a 

 latticed sphere of silex supported on a slender stalk ; the diameter 

 of the shell is about -g-i^ inch, and the length of the stalk about 

 tA^tt inch. See Model 7 in the Case. 



FORAMINIFEBA OR ReTICULARIA. 



The majority of the Foraminifera form a shell of carbonate of 

 lime ; in some, the shell is composed of cemented sand, mud, or 

 sponge spicules, and, in a few species, of membrane or silex. The 

 series of Foraminifera mounted on slides is arranged in ten families 

 according to Mr. H. B. Brady's classification, an enlarged figure 

 being placed below each slide. The classified series is preceded by 

 an introductory account of the group. The small plaster models on 

 steps and on the floor-shelf represent selected types, both living 

 and fossil. 



Wlien the skeletons of Foraminifera were first discovered, they 

 were supposed to be the shells of tiny Cephalopods or other Molluscs. 

 Great was the sensation in the scientific world when, in 1835, 

 Dujardin found, from observation of the living animals, that the 

 builders of these complicated shells consisted simply of apparently 

 structm-eless protoplasm, which extruded root-like trunks of branch- 

 ing and anastomosing threads whereby the creatures crept along 

 (Figs. 4, 5). Accordingly he removed these organisms from the 

 Mollusca and placed them in a new group, Ehizopoda {rhiza, root ; 

 pom, foot). 



Foraminiferal shells either have only one or a few main apertures 



