156 PAUL S. GALTSOFF. 



On coalescence the inner granular protoplasm of the archaeo- 

 cytes remains unmixed ; the granuloplasm of various cells occupies 

 a definite portion of the aggregate, while the hyaloplasm forms 

 a common mass surrounding the whole group. 



By pressing the coverglass under which the aggregates are 

 lying or by violently shaking a dish containing aggregates the 

 cells can be separated after which they are able to coalesce again. 



The amoeboid movement of the archaeocytes is irregular; some 

 of them move actively while the others remain motionless or 

 creep very slowly over the bottom. There is no visible difference 

 between sluggish and active archaeocytes. Frequently after 

 being immobile for 60 or 80 minutes the archaeocyte becomes 

 active and starts to move rapidly. 



In many cases when two archaeocytes coalesce the aggregate 

 remains motionless for a few minutes after which it starts to 

 move in another direction. The coalescence with a small dermal 

 cell or with a choanocyte does not disturb its movement; it con- 

 tinues to move as if there w r as nothing in its route. 



The small dermal cells move very slowly or not at all. The 

 choanocytes do not display an amoeboid movement but are able 

 to displace themselves by means of their active flagella. 



The ectoplasmic layer of the isolated archseocytes is fluid and 

 sticky. The cells easily adhere to different objects which come 

 in contact with them. The adhesiveness of their protoplasm 

 can be strikingly seen in a suspension containing starch grains. 

 Each aggregate formed in such suspension is surrounded with a 

 ring of starch grains. This occurs because the starch grains ad- 

 here strongly to the cells; as the aggregates move and turn in 

 different directions they become surrounded with grains with 

 which they accidentally come in contact. When moving the 

 cells are able to push along or to carry various foreign bodies 

 which they meet in their route. In one observation a small aggre- 

 gate was found strong enough to push a group of five starch 

 grains each of which was larger than the aggregate itself. 



The formation of the aggregate from dissociated tissue cells is 

 due to the motility of certain archaeocytes and to the stickiness 

 of their outer layer of protoplasm. The various cells are uniform- 

 ly distributed in the suspension and over the bottom of the dish; 

 each active archaeocyte moves back and forth over a definite 



