E. MARSHALLT. — THESOCYTES. 177 



remnants of the spherules appear simply of a darkish hue. 

 Weak formalin extracts the yellowish coloring matter of the 

 spherules but preserves them in their original form. When 

 acted upon by alcohol, their color likewise dissolves away, while 

 their shape, evidently owing to shrinkage, becomes more or less 

 irregular, losing its homogeneous appearance and often producing 

 vacuoles within. 



In sections of specimens which had been fixed with corrosive 

 sublimate or with strong alcohol, I found the cells contracted to 

 an irregular or tubercular shape (PL IV, fig. 25). In most cases 

 the spherules had wholly disappeared, leaving behind vacuole- 

 like empty spaces once occupied by them. But their disappear- 

 ance was in many cases not complete, there being left in these 

 cells a greater or less quantity of the matter in the form 

 of irregular clumps, conglomerates or granules. Kemarkable is 

 the fact that occasionally some or nearly all of the spherules in 

 a cell are found to even retain their original form and arrange- 

 ment. It may be that certain spherules are of a somewhat firmer 

 consistence than others and are thus capable of resisting to a 

 greater or less degree the destructive influences of the hardening 

 reagents. 



F. E. Schulze Çgga, p. 207) has found, in the three Arctic 

 species studied by him, the 'Knollen' well preserved in all 

 specimens which were first treated with sublimate solution, but 

 more or less completely dissolved away in those which were 

 hardened in strong alcohol from the first. In U. marshalli the 

 appearance of the thesocytes, as seen in sections cut after the 

 usual processes of dehydrating and paraffine-imbedding, seemed 

 to be much the same, irrespective of the different reagents into 

 which the specimens were first thrown. 



