NO. 4 



FORAMINIFERA CUSHMAN 



were very low types of animals belonging to the Protozoa was not 

 recognized until much descriptive work had been done upon them. 

 They are now known to form a definite group of the Protozoa, and 

 much is known of the animal as well as the test that it makes about 

 itself. 



LIFE HISTORY 



Two distinctive forms of many species have been recognized. In 

 general one form is large and rare, the other smaller and much more 

 abundant. Sections of such specimens show that the large form starts 

 with a very small initial chamber or proloculum and is called the 

 microspheric form. The small form, on the other hand, commences 



Fig. I. — Idealized section of microspheric form of Nodosaria showing the small 

 proloculum and the long test. 



Fig. 2. — Idealized section of megalospheric form of Nodosaria showing the 

 large proloculum and the short test. 



with a much larger proloculum and is known as the megalospheric 

 form. Two such sections are shown here, figures i, 2. It has been 

 discovered that the large microspheric form, when it reaches its 

 adult stage, develops many nuclei, each of which secretes about it a 

 test, and on the breaking down of the " parent " wall these " young " 

 escape into the water and become new animals. This is the typical 

 asexual method of reproduction. The smaller megalospheric form 

 may also do this. Another manner of reproduction may be shown by 

 the megalospheric form, where, when the adult stage is reached, the 

 protoplasm breaks up into a great many very small masses and 



