274 JERKM1A1I S. FKRCU -MX. 



period the fibers had so increased in numbers that they neces- 

 -arily laid in relation to the cells. 



The weak point in Merkel's deduction appears to be the dis- 

 regard of the locomotive properties of mesenchymal or youn^ 

 connective ti-Mie cells. If these cells, except for the incidents 

 of mitosis, are stationary, then Merkel's observations would 

 render conclusive evidence to support the theory of the extra- 

 cellular origin of libers. But that such cells possess at least a 

 limited power of motion simulating the anm-boid character 

 has long been known. An adequate theory must account for 

 the activity of these cells. Merkel's theory presupposes them 

 to be stationary till fibers have appeared and only later to 

 acquire amoeboid characters. 



In -e.irching for a tissue which would offer opportunity for 

 the study of the activities of connective tissue cells in the living 



SW1PM. Mf, S.50I 5.51 5.5Z 



68 



6.00 



6 - /0 



6.07^7 6.08 6.09 ^4 



oJ L , VS^-A ^v/ 



FIG. I. < Hitlincs of a stc-llate conned iv ti^^uc ci-11 in tlu- caudal fin of a I-'uiiiln- 

 /HV rinl)i >(> 4.5 mm. long (one clay alter hatching). The figures record the moment 

 of completion of each drawing, the whole ol>~er \-ati on extending over a period of j.j 

 minutes. The fish was afterward returned to water and swam for two days I" 

 li'-iny killed I'll tiirther histoli .yical use. The cell observed corresponds in appear- 

 ance with that -hown liy \\'. 1- leiiimin.- i \r,h. I. Aunt., 1897, Fig. 9, Plate \"I.) 

 in the me-entery of a Snlnni:itiil?r lai \ a. It slmws active amoeboid motion and 

 ash e change- oi iiiim. It- locomotion was not recorded, it was (|itite limited. 

 X 800, camera lucida. 



animal under normal conditions, 1 have found that the median 

 tin o| voinr; lish embr\ - o-> allonh a subject tor stud\' \\ hich throws 



on Merkel's observations. 



