Vohivie II. July, l8<^8. Nuvibcr I. 



ZOOLOGICAL BULLETIN. 



FILOSE ACTIVITY IN METAZOAN EGGS. 



ETHAN ALLEN ANDREWS. 



One who has not studied Hving Foraminifera or Radiolariacan 

 get only an inadequate conception of the remarkable activities 

 exhibited by the delicate protoplasmic extensions that form in 

 such protozoans the thread-like pseudopodia. The figures and 

 descriptions in text-books of zoology, in Verworn's Physiology, 

 in Butschli's Protozoa, or in special monographs naturally fall 

 short of complete expression of the changeableness as well as 

 the extreme delicacy of certain of these processes, though they 

 teach us that the sensitive, contractile, coordinating powers of 

 protoplasm may here be expressed in filaments of exceeding 

 tenuity and inconstancy of form and position, — in flowing, 

 liquid, apparently homogeneous protoplasm. 



Such filose phenomena were practically unknown in Metazoa 

 till a recent paper^ described their occurrence in the eggs, polar 

 bodies, blastulae, gastrulae, and larvae of certain echinoderms. 

 Here the cells put forth protoplasmic threads of excessive 

 delicacy, that may branch and anastomose, elongate or shorten. 

 By means of such filose processes the cells become connected 

 amongst themselves, and, as these connections are living 

 material comparable to the sensitive pseudopodia of many 

 Protozoa, their importance in understanding the coordination 

 of cells and their subordination to the entire mass, during the 

 animals' development, was emphasized.^ 



Having been shown the filose threads in living starfish eggs, 

 I have been able to observe the less attenuated ones present in 



1 Andrews, G. F., " Some Spinning Activities of Protoplasm in Starfish and 

 Echinus Eggs," Jourii. of Morph. Vol. xii. 1897. 



