E. MAESHALLT. — TKABECUL.E. 159 



are always very small, fiuctuating within only an inconsiderable 

 range of variation in this respect ; in shape they are constantly 

 spherical or approximately so. In E. marshaUl they rarely, if 

 ever, exceed 2 /'- in diameter, while the smallest measure about 

 l\'2/^5 — a variation of say less than half a //. This does not quite 

 agree with Schulze's statements. However, this fact alone would 

 not perhaps have led me to the above skepticism, were it not 

 for another circumstance which serves to account for the size 

 ascribed by Schulze to the ' larger nuclei.' 



As I have before indicated (p, lö4, under 2.), I hold that 

 the ' larger oval nuclei ' Schulze's in the connective substance of 

 both E. aspergUlum and S. arctica are nothing else than, or 

 should at least include among them, the well-defined cells which 

 I call the archœocytes (PL Y, figs. 36, 39, 43 ; arch.). For the 

 nature and characteristics of these cells, the reader is referred to 

 the special chapter devoted to them. Here suffice it to mention 

 that these cells are exceedingly liable to be taken for mere nuclei, 

 and that their distribution in the trabecular system agrees on the 

 whole with that ascribed by Schulze to the ' larger nuclei ' in S. 

 arctica. On the other hand, I find no mention of these cells as such 

 in the descriptions given by that investigator, though they have 

 been undoubtedly seen by him. At all events there can be no doubt 

 whatever that the ' larger nuclei ' seen by him in groups in the 

 immediate proximity of the flagellated chambers and taken for 

 possible genital cells ('ig«, p. 99),'-' are the same as my archœo- 

 cytes, which thus seem to have been only partially recognized in 

 that they were errorneously considered as nuclei and not as com- 

 plete cells. If this be so, then the discrepancy in our observations 



* The same groups of cells, likewise considered as possibly concerned with reproduction, 

 were also seen before by Schcjlze in Farrea occa ('87, p. 285). Here the elements in the 

 groups are described as ' cells,' with nuclei which stain with special readiness. 



