76 ANDREWS. 



The processes sprung up close on actual splitting apart of 

 the cells, so that at no time was it usual for the products of a 

 cleavage to be physically separate from each other, though with 

 slightly less efficient optical conditions one could see no con- 

 nection between them. 



[84] Continuity was, in fact, hardly destroyed at any point 

 of the substance in cell-division before restored by filose pro- 

 jections from both the sister cells. 



The phenomena were more profuse in earlier than in later 

 stages. In my most carefully preserved specimens I have ob- 

 tained but a much reduced number of fine spin processes, and 

 these were somewhat altered. No reagent, not even heat, is 

 quick enough, nor can one be applied so quickly as not to give 

 the sensitive living substance time to react. Even with great- 

 est care such processes are liable to be withdrawn during kill- 

 ing operations, and further manipulation for sectioning is very 

 destructive to these delicate formations which when living 

 have the sensitiveness of end-organs and a rapidity of transfor- 

 mation almost equal to that of thought processes. On the 

 other hand, the reader is earnestly warned against pseudo-filose 

 threads and webs which seem to be caused by chemicals and 

 section fixatives, — and it is not impossible that slow killing 

 may stimulate cells to abnormal or unaccustomed spinning. A 

 student must have large familiarity with such processes, not 

 only as to habit and type of formation in normal living eggs, 

 but as seen among the Protozoa, especially the Protoplasta, 

 before risking predication as to appearances found in preserved 

 or sectioned material. 



That portion of sister cells which was at some moment 

 internal to both as taken together, was usually last to become 

 fused, and here the filaments could be longest watched. 



Not only between sister cells of a recent cleavage did filose 

 processes pass. In the four-celled stage, the central cavity was 

 filled with a web of these filaments, as was also the space 

 between the group and the ^%g membrane, where they were, 

 as a rule, more delicate. In the eight, sixteen, thirty-six celled, 

 and intermediate, stages, — for I find the cleavage to be by no 

 means regular, as my text-books asserted, but to follow a spiral 



