II 



PHYLUM PROTOZOA 



55 



perforated spiral shell, called Hastigerina (Fig. 37), a very remark- 

 able modification of this condition of things obtains. The shell 



F 







i &4r^ 8 **^ ' * / 



. . *J& A""" i^^3^ "' *" Q 



~^*>i O*"* ' '' SL/ 



*:-fS 



^\:^'- f 





 r? t 



-.!,.'-* ;. ; ^ 



t-L. 



FIG. 38. Dimorphism and alternation of generations in Polystomella crispa. The arrows 

 indicate the direction of the life-cycle. A, young megaspheric individual; B, full-grown 

 megaspheric individual, decalcified ; C, megaspheric individual in the act of spore-formation, 

 the protoplasm leaving the shell in the form of flagellulas ; D, flagellula more highly 

 magnified ; E, microspheric individual developed from a flagellula ; F, microspheric individual 

 in the act of producing amoeboid embryos. (From Lang, after Schaudinn.) 



.) is surrounded with a mass of protoplasm (plsm.) many times 

 its own diameter, and so full of vacuoles as to present a bubbly or 



