THE PARABLASTIC TISSUES. 



271 



subsequently disappears and the nucleus returns to its central 

 position. Such changes recur many times, the equatorial con- 

 striction of the cell being more marked with each repetition of 

 the phenomenon. At length the nucleus is seen to be elongated 

 and it ultimately divides, and the two new nuclei rapidly 

 separate ; the constriction then becomes deeper and deeper, and 

 in a few minutes the cell is divided completely by it. The 

 process is precisely similar to that which has been described in 

 the agamic division of the Infusoria. 



, m M 



FIG. 17 bis. Blood corpuscles (leucocytes) of the adult larva : /, living corpuscles, show- 

 ing the amoeboid condition, in d the nucleus is also amoeboid ; 2, the same, treated 

 with magenta, showing the various appearances produced by the action of the 

 reagent ; j, a living cell in several stages of direct division (all drawn with T V oil 

 immersion lens). 



The blood corpuscles of the resting larva, nymph and imago, 

 when fixed by steam and properly stained, sometimes exhibit 

 distinct but irregular nuclear figures asters, diasters, etc. and 

 several nuclei are frequently seen in one cell ; hence it might be 

 inferred that karyomitosis occurs in the division of the nucleus, 

 as above described, although the conditions of the observation 

 are such that this could not be seen in the living corpuscle. 



The method I adopt for the examination of the nuclear figures 



