Maech 5, 1897.] 



SCIENCE. 



389 



3. The sum total of the energies of these 

 lesser units constitute cellular life. 



4. Differentiation is caused by specific 

 irritation of certain kinds or elementary 

 units, instigating these to multiplication 

 and therefore to supremacy over the other 

 units. 



5. The cell does not lead a double life ; it 

 leads only one life, namely, an independent 

 life. Tliere is, in fact, only one life that we 

 know of. 



6. The axiom that a function presupposes 

 cellular structure is not proved. Structure 

 presupposes function is more acceptable, as 

 it may be supported by direct evidence. 

 Cellular structure becomes more compli- 

 cated if the function of the cell is more 

 energetic. 



7. Structure is a side product formed 

 during the exchange between stimulus and 

 reaction. (Was supported by examples 

 from the organic and inorganic world.) 



8. The elementary units of the cell are 

 partly demonstrated in the microsomes, 

 chromatin granules and centrosomes. The 

 microsomes are of different kinds, some of 

 which were demonstrated by slides. 



1. Origin of the Centrosomes in the Unfertilized 

 Egg of Chodopterus. 



2. The Behavior of the Centrosomes during the 

 Maturation and Fertilization of Chcetopterus. 

 A. D. Mead. 



There is in the egg of Chsetopterus a defi- 

 nite body, the centrosome, which is not an 

 artifact, and which is not identical with the 

 centrosphere or astrosphere, though the 

 latter is sometimes present. 



In the ' oocite of the first order,' i. e., the 

 un maturated egg, the centrosomes arise by 

 a modification of pi'e-existing cytoplasmic 

 structures. Those of the first and succeed- 

 ing cleavage spindles are identical with, or 

 derived directly from, the male centro- 

 somes, which are probably brought into the 



egg with the middle-piece of the spermato- 

 zoon. 



The centrosomes, whatever their origin, 

 are capable of growth and multiplication 

 and persist through at least several cell 

 generations. 



There is no union of male and female 

 centrosomes during fecundation — no ' quad- 

 rille of the centers.' The female centro- 

 somes entirely degenerate, and therefore 

 cannot be considered a special means for 

 conveyance of hereditarj' qualities. 



The centrosphere, a differentiated region 

 about the centrosome, gives a different re- 

 action from the centrosome, on the one 

 hand, and the rest of the cytoplasm, on the 

 other, both in point of color and resistance 

 to certain reagents. Corrosive-acetic and 

 certain other reagents will sometimes com- 

 pletely destroy the centrosphere, though the 

 rays and other structures are fairly well 

 preserved. 



The centrospheres, unlike the centro- 

 somes, appear and disappear with each suc- 

 ceeding karyokinesis. When they are pres- 

 ent the cytoplasmic rays of the aster are not 

 so strongly developed as when they have 

 disappeared and the rays diverge directly 

 from the centrosomes themselves. 



The centrosomes divide and move apart 

 within the centrosphere for a considerable 

 distance without altering the spherical shape 

 of the latter structure. 



On the Origin of the Centers of the First Cleav- 

 age Spindle in Unio Complanata. F. E. 



LiLLIE. 



After the formation of the second polar 

 body the inner centrosphere and a large 

 part of the aster become converted into 

 archoplasm, against which the egg nucleus 

 lies. The archoplasm is vesicular(or retic- 

 ular) in structure, and contains the centro- 

 some, though the latter cannot be distin- 

 guished on account of the entire disappear- 

 ance of radiations. The sperm nucleus 



