NOTES AND MEMORANDA. 95 



the other hand, considered them as isolated. Carpenter 

 (186!^) was the tirst to discover these. After some details 

 as to the number and arrangement of these sarcode processes 

 which the author found to be of a more hyaline and less 

 granular character than the rest of the sarcode-body, as well 

 as more prone to imbibe staining fluids, he proceeds to 

 describe his experiments in order to test the presence of a 

 nucleus. 



He first directed his attention to the median primary 

 chamber, distinguished from the rest by its globular figure, 

 but in it he never found by any method a nucleus or any- 

 body at all like it ; sometimes, indeed, a few clear round 

 spots could be seen, but pressure constantly proved these 

 were merely drops of probably oleaginous nature, and with- 

 out any wall ; sometimes they could not be seen. Almost 

 giving up the research in despair, he was much surprised 

 one day, on looking at a specimen whence the shell had been 

 removed, to notice a spot in one of the segments about 

 midway of a difi"eient aspect. He then stained the whole 

 object in a decoction of logwood, and in order to render the 

 preparation clear, then applied a dilute ammoniacal solution. 

 To his great delight he now saw at the previously mentioned 

 spot, lying in the now clear, blue, granular sarcode, a violet- 

 coloured globular body (0"056 mm. in diameter) with a 

 distinct, thick, outer membrane and clear contents, in which 

 could be recognised several strongly refractive ellij)tic or 

 roundish structures of different sizes (whether to be regarded 

 as nucleoli, or as produced by the treatment, the author 

 leaves undetermined) — in a word, a nucleus of almost typical 

 structure. Treating a great number of Polystomella forms 

 in the same way he always arrived at the same result though 

 with some modification. 



Ordinarily in each Polystomella but one such nucleus was 

 to be found, and this, indeed, always in the middle of one 

 of the middle segments ; in rare cases he found two nuclei 

 occurring in adjoining segments ; only once did he see the 

 two nuclei separated by a segment without any nucleus; 

 and once he saw three nuclei in one animal — two in imme- 

 diate sequence, and separated from the third by a segment. 

 The nucleus in older examples occupies some one (or two) 

 of the middle third of the whole number of chambers ; but 

 in very young forms (4-10 chambers) he found the nucleus 

 far behind, say in the second chamber. Sometimes, indeed, 

 the nucleus was not confined to a single chamber, but one 

 ])art of it in one, the other in the adjoining chamber; in 

 such cases the segments remained hanging together by a 



