NOTES AND MEMORANDA. 97 



of others being mainly confined to the shells. Although 

 M. Schultze was of opinion that, on the whole, the Foramini- 

 fera were Avithout nucleus, still in Rotalia venetahe described 

 a clear body, which was rendered more distinct on the appli- 

 cation of acetic acid, and which he was inclined to regard as 

 a nucleus, though unable to study it more exactly. He ob- 

 served something similar, too, in an example oiTextilariapicta, 

 in which he succeeded " in isolating from the two last cham- 

 bers a nucleus-like structure." Also he had described 

 nuclei in Gromia oviformis. 



Under the circumstances of the doubt in which the ques- 

 tion was involved HertAvig availed himself of the oppor- 

 tunity of a visit to Heligoland to submit living Foraminifera 

 to a renewed study, and he also obtained from Professor 

 Haeckel examples from the Mediterranean sea. 



But he soon found out that no definite result was to be 

 gained by the examination of only fresh specimens, so he 

 applied himself to the use of reagents. He found that 

 acetic acid, employed by Max Schultze, was of no 

 service : it only coagulated the substance, and rendered the 

 object too dark. Better results were obtained by the appli- 

 cation of dilute solution of chromic acid ; in it the proto- 

 plasm swelled and became partly extruded from the shell, 

 remaining tolerably transparent ; but then a coagulation set 

 in, darkening the preparation, accompanied, indeed, by a 

 bleaching-out of the brown pigment ; but as regards the 

 coagulation, the chromic acid was no improvement on the 

 acetic acid. Tn most cases, however, it sufficed to render 

 the nuclei evident ; in others, again, he had to take refuge 

 in staining; for this purpose he used Beale's carmine fluid. By 

 its application he obtained favorable results in preparations 

 which had lain for a day in chromic acid, which had then been 

 washed out by frequent renewal of the water for several hours. 



Young examples of Miliolse offered the most conclusive 

 results. The youngest were single chambered in the fresh 

 state ; in spite of the pellucid character of the shell, he 

 could not discover a nucleus with any certainty; he could 

 only distinguish a homogeneous, nucleus-like spot. This, 

 however, coagulated on application of chromic acid into a 

 sharply-contoured, minute circle (0"01 mm. in diameter), 

 disclosing within a sharply-contoured little body (0004 mm. 

 in diameter). Still more distinctly did this structure come 

 out with " Beale's fluid," tlu; inner body assuming a ruby 

 red. Whether this structure represents a iiucleus differen- 

 tiated into nucleolus and nuclear membrane, or (in the fresh 

 state) a homogeneous nucleus, merely assuming, owing to 



VOL. XVII. NEW SEH. G 



