154 T. IJIMA : HEXACTINELLIDA. I. 



of what I have seen of the same nuclei in E. niarshalli and in a 

 number of other Hexactinellid species, the histology of which 

 will be duly remarked upon in the future numbers of this series 

 of Contributions. On the contrary, the occurrence on the syn- 

 cytial trabecular thread, of certain cells, which on account of 

 their well-defined spherical or ovoid bodies cannot possibly be 

 pinacocy tes, is quite common. The projected state of the trabecular 

 nuclei, as they have come under my observation, was in nearly 

 all cases apparently due to the simple fact that the space in the 

 protoplasm was not sufficient to completely include them. The 

 unilateral situation of the nuclei, especially in the thinner 

 trabecular thread, may also be considered as the result of an 

 uninterrupted and most effective bringing about of protoplasmic 

 continuity, vvhich may be of primary importance to the trabecule 

 considered as a connective substance. 



2) Somewhat larger and more oval-shaped nuclei with little 

 protoplasm around them, giving simple stellate or spindle-like 

 shape to the cells. These appear to have been seen in relatively 

 smaller numbers and are regarded as representing connective- 

 tissue cells lying in a hyaline matrix. It occurs to me likely 

 that the 'nuclei' here referred to, correspond in part at least 

 to certain distinct cells, which I will describe in a later chapter 

 under the designation of arch^eocytes. My grounds for holding 

 that opinion will be given presently in connection with ap- 

 parently the same ' nuclei ' described by Schulze from Schau- 

 clinnia arciica. Tlie nature of the protoplasmic space around 

 the alleged nuclei, seen by Schulze in E. aspergillum but apparent- 

 ly not in S. arctica, remains incomprehensible to me, unless it 

 be considered to be a part of the protoplasm of the trabecular 



