THE LIVING SUBSTANCE. 



75 



abnormal eggs where the excess material came, it was plain, 

 from an underlying structure of Biitschli, which might be largely- 

 involved if the egg's condition were markedly abnormal. 



There was no true intermission, except very locally, at any 

 time during development up to the blastula stage when the 

 activities ceased externally to the mass for a short time, only 

 to burst out once more as cilia formation. This organized 

 manifestation terminated them peripherally, so far as I could 

 see in following larval stages up to formation of the skeleton 

 in three dimensions, or to formation of the proctodaeum. To 

 the end of my observations, filose activities persisted internally 

 as delicate processes crossing the blastocoele and attaching 

 themselves to its walls, to ectodermal processes, or to those of 

 mesenchyme cells. For a time after gastrulation, the inner 

 ends of the ectoderm cells were elongated, and the optically 

 wedge-shaped interspaces so formed were crossed by strands 

 and webs of filaments. 



There was no intermission in the course of development 

 which could be interpreted as sympathetic with karyokinetic 

 rhythms, except a momentary cessation near and at the line 

 where a cleavage split was to pass. Following in the path of 

 cleavage as fast as blastomeres became split off from each 

 other, there sprung up renewed spinnings. These- filaments 

 extended themselves, with or without ramifications and anas- 

 tomosis, but always with markedly less of these phenomena 

 than belonged to peripheral spinnings, until they first reached 

 filaments, or the pellicle, of the sister cell which was being sep- 

 arated. Filaments between cells held, as a rule, a more direct 

 course, ramifying less than those of the periphery, and having 

 a tendency to structural reduction, seen finally as change of 

 optical quality. These traits became more or less emphasized 

 in them after their first attachment to a sister cell. With- 

 drawing their branches, several filaments would fuse longitu- 

 dinally with each other to form bands, or bridges, rather than 

 attached rays, of protoplasm between cells. At certain stages 

 in cleavage the structurelessness and viscosity of aspect in 

 these connections increased, that is, at such tune as the cells 

 drew together again. 



