196 CORA J. BECKWITH 



fluids. Chemical tests were made on material fixed in indifferent 

 killing fluids, such as alcohol, hot water and formalin in which 

 the formic acid is neutralized. A large number of stains were 

 also used, the results of which are again shown in table 1. Some 

 experiments with 'intra-vitam' stains gave most useful results, 

 which are recorded in table 2. 



Other methods to determine the chromatic nature of the proto- 

 plasmic granules have been tried, such as artificial digestion of 

 fresh or alcohoHc tissue, and tests for nucleo-histone and phos- 

 phorus (Mann '02), The possible proteid nature of the granules 

 was also investigated by the use of Millon's reagent. Experiments 

 on the staining reaction of egg-albumen which had been fixed 

 with various ones of the same killing fluids were also made. 



B. PROTOPLASMIC STRUCTURES OF THE MATURE EGG 



It is essential to difl"erentiate the protoplasmic structures of 

 the mature egg in order to make clear their relation to the extra- 

 nuclear granules which I prefer to call 'pseudochromatin-granules.' 

 The nucleus will therefore not be considered at present. The 

 egg of Hydractinia is large and filled with various granules and 

 spheres which fall into four groups : 



1 . Small simple yolk-spheres which vary greatly in size and occur 

 throughout the egg. 



2. Compound yolk-spheres, the largest elements in the egg. 

 They form in general a crescentic layer around the egg, a little 

 below the surface and are found to some extent throughout the 

 center of the egg. 



3. Oily bodies, about the size of the small yolk-spheres, which 

 darken in osmic acid and are often irregular in shape. These 

 pervade the whole egg. 



4. Mitochondria, small bacillus-like rods, slightly more abundant 

 at the surface of the egg, but rather evenly distributed throughout 

 the protoplasm. 



These elements of the mature egg lie in a finely granular proto- 

 plasm, which stains entirely with plasma stain, that is, there are 



