CENTRIFUGAL FORCE ON EGGS OF CREPIDULA . 357 



More fluid part More solid part Author 



^ , , , > fHeitzmann, 1873 



Ground substance r, .■ ^ L-. 1000 



_, , , ) Keticulum < Carnoy, 1883 



Enchylcmma / [vanBeneden, 1883 



Alveolar Substance Interalveolar Substance Biitschli, 1873-1892 



Paramitome Mitome Flemming, 1882 



Hyaloplasm Spongioplasm Leydig, 1885 



Trophoplasm Kinoplasm Strasburger, 1892 

 Etc. Etc. 



Some of the earlier students of the cell considered that only 

 one of these substances was 'living/ though they differed as to 

 whether it was the more fluid or the more solid part. Wilson 

 ('00, p. 30) concludes that ''we are probably justified in regarding 

 the continuous substance (i.e. spongioplasm, inter-alveolar sub- 

 stance, kinoplasm) as the most constant and active element 

 and that which forms the fundamental basis of the system, 

 transforming itself into granules, drops, fibrillae, or networks in 

 accordance with varying physiological needs." With this opin- 

 ion I entirely agree. ! 



In addition to these two substances protoplasm contains many 

 other parts, some of which as Wilson suggests are formed prob- 

 ably as differentiations of the spongioplasm, others perhaps as 

 differentiations of the hyaloplasm. Among the substances 

 which are embedded in the protoplasm, but are not a part of it, 

 are the 'inclusions' such as oil, water, yolk, etc. 



Lillie ('06, p. 156) says of the protoplasm of the egg of Chaetop- 

 terus, "The ground substance is a suitable name for the fluid that 

 contains and suspends all the granules and droplets; if these were 

 imagined removed it would preserve a faithful semblance of the 

 egg. Thus it is regarded as forming the external pellicle and 

 as continuous through the nuclear membrane with the nucleo- 

 plasm." Speaking of the vibrations of the microsomes and 

 spherules in living protoplasm, Lillie says, "No one who has 

 studied these movements, as I have done for hours at a time, could 

 believe that the microsomes are nodal points of a network, or are 

 connected by filaments as they appear to be in the best stained 

 sections. One is forced to conclude that they have freedom of 

 movement in all directions, i.e., that they are suspended in a 



