ON THE LIFE-HISTORY OF THE FORAMINIFERA. 145 



scattered through the protoplasm of the terminal chambers. 

 These are sometimes uniformly distributed, sometimes disposed 

 in groups (fig. 30). In some cases these nuclei appear as com- 

 pact, nearly uniformly stained bodies, in others they contain 

 many round vacuoles (fig. 31). It may be observed that all the 

 nuclei in such a specimen appear to be vacuolated to the same 

 degree, whether it be much or little. 



Two examples of the megalospheric form in which the large 

 nucleus has disappeared (collected on May 31) present different 

 conditions. 



In one of these (fig. 27), which is composed of eighteen 

 chambers, the whole protoplasm except that of the last •^jwo 

 chambers is broken up into small spherical masses, 3 to 4 /i in 

 diameter, the centre of each of which is occupied by a nucleus. 

 The nuclei are in the phase of karyokinetic division (fig. 28), 

 in which the chromatin elements have separated from one 

 another, and present the appearance of two distinct parallel 

 bands, 1"5 ft in length, separated by achromatic substance. 

 From what is seen in the specimen next described it appears 

 that the spherical masses are about to divide to form spores. 

 In the two terminal chambers numbers of nuclei arc present, 

 but they are not in process of division, and the protoplasm 

 though much vacuolated is not broken up into spheres. I am 

 not able to account for this condition of the terminal chambers. 



In the second specimen (fig. 32, a), which is composed of 

 seventeen chambers, the whole of the protoplasm is divided up 

 into spherical masses 3 to 3"5 fi in diameter. Each contains a 

 nucleus, and a trabecular structure of the protoplasm can be 

 seen in the interior. Between adjacent spheres a delicate net- 

 work is seen, and in the terminal chambers a curved strand of 

 this reticulum may here and there be detected, having the 

 appearance of a flagellum (fig. 32, b). 



Four days after this specimen was collected (June 4), I 

 happened to be examining a partially empty shell under the 

 microscope, and saw at one point through a transparent region 

 of the wall of one of the chambers, an active movement in 

 the interior. I crushed the specimen under a coverslip, and 



