THE AQUARIUM BULLETIN 



43 



tracts simultaneously, and then slowly 

 uncoils in perfect unison. When con- 

 tracted it has the form as shown in 

 Fig. 5. Not only does each individual 

 stem coil up, but also the parent stem 

 for its entire length, and the propor- 

 tion of the colony is diminished to 

 a fraction of its extended size. Any 

 slight disturbance, such as a slight tap 

 on the slide, will cause the colony to 

 contract. This little trick of the Vor- 

 ticella is indeed remarkable and inter- 

 esting. How the entire group can 

 respond to the impulse simultaneously 

 and all act in such perfect accord, as 

 if by some master control, is beyond 

 our analysis. 



The formation of a colony of V. 

 nebulifera is brought about by the 

 multiplication of one animal. This 

 process of reproduction is termed 

 fissiparous multiplication, and the suc- 

 cessive stages may be followed as 

 shown by the numbered individuals 

 on the drawing. 



No. 1 illustrates the beginning of 

 the division. An enlargement of the 

 body is noted with an indication of a 

 longitudinal cleverage at the center of 

 the upper edge. At this stage various 

 internal changes may be seen to take 

 place under higher power. The cilia 

 action has become greatly subdued. 

 The tension of the stalk lessened, but 

 still continues to contract with the 

 other members of the colony. 



No. 2 shows the body division very 

 distinctly. The internal changes have 

 ceased. A nucleus may be indicated, 

 one each side of the division. The 

 cilia are again active. The animal 

 appears to feed and employ itself as 

 if no great part of its life history was 

 being enacted. 



No. 3 shows the body division com- 

 pleted, but the two newly formed 

 animals still held together by the old 



stalk. Any one of the two may fold 

 in its cilia, and in other ways act in- 

 dependent of the other, or they may 

 both act in unison, folding and con- 

 tracting the stem with the colony. 

 Finally the stem will divide and the 

 two animals will separate with a jerk, 

 but still remain attached to the parent 

 stem. One of the two may eventually 

 break away completely, swim free and 

 attach itself to some suitable support, 

 and by the same process of reproduc- 

 tion establish a new colony. 



It is thus seen that the animal knows 

 no death, unless by accident. The old 

 body simply divides into two new 

 bodies, the parent disappearing in the 

 off-spring. 



An intensely interesting and valu- 

 able scientific work by Dr. R. W. 

 Shufeldt will appear in the Novem- 

 ber issue of THE AQUARIUM 

 BULLETIN. 



It is well known that the United 

 States Government maintains a won- 

 derful collection of fossil fishes in 

 the New National Museum at 

 Washington. 



What to many might be common- 

 place through lack of appreciation, 

 becomes of paramount interest when 

 properly explained by a master- 

 student. 



The geneology of the Cichlidae and 

 other families is presented in a 

 most readily understood form. 



In the December number a most 

 unusual article on the different fishes 

 of Bermuda by Dr. R. W. Shufeldt 

 will appear. BLJLLETIN readers will 

 be amply prepaid for waiting for 

 December number out December 1st. 



