ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 35 



The specimens are spheroidal or ovoiclal in shape and with a root-tuft ; 

 the surface bristles with a pile-like coat of spicules, which are mostly 

 protriaenes. Arranged round the sides of the sponge are flask-shaped 

 recesses with oval or circular orifice, and with the margins 'guarded by a 

 fringe of needles rising above the general surface ; on the upper part of 

 the surface are smaller orifices, likewise surrounded by a spicular fringe. 

 Sollas regarded the flask-shaped recesses as being either vestibules or 

 cloacas, and called them oscules for convenience of description. Kirk- 

 patrick concludes that in the seven species of Cinacliyra the depressions 

 on the surfaces are probably in every instance poral vestibules, the 

 oscules being separate and distinct. 



Studies in Spicule Formation.* — W. Woodland has studied in 

 particular the spicule formation in Sycon coronata and >S'. ciliata. His 

 results are very different from those of Maas, as may be thus shown : 



Maas. Woodland. 



Each monaxon arises in a single No trace of the spicule occurs 



mother-cell. until the mother-cell has con- 



stricted into two nucleated por- 

 tions. 

 There is never more than one There are never less than two. 

 cell on the smaller monaxons. 



The large monaxons have nu- The largest monaxons, in the 



merous formative cells upon them, two species studied, have never 

 derived from the dermal layer de more than two formative cells ; 

 novo. when there are four, as in some 



Ascons, these probably arise from 



the original mother-cell (or cells). 



The triradiates arise each in a The triradiates are derived from 



single mother-cell as a concretion, three mother-cells which have asso- 



but at a later stage they bear ciated together, and built up by 



several formative cells. their six division products. There 



are no additional formative cells. 



The author expounds two laws of spicule formation : — (1) the necessity 

 of the proximity of the cell-substance to the site of lime secretion ; and 

 (2) in Calcarea, the necessity of the presence of two masses of dermally- 

 derived cell-substance, between which the young spicule is deposited. 

 From these he proceeds to explain the existence of the three kinds of 

 spicules characteristic of calcareous sponges, showing not only why the 

 three kinds occur, but also why other kinds do not. The modes of dis- 

 position and secondary forms of the spicules are the inevitable results 

 of environmental influences operating during the course of each indi- 

 vidual ontogeny. 



Protozoa. 



Structure and Movements of Protoplasm.f — K. C. Schneider 

 discusses the structure and movements of the plasma in Foraminifera, 



* Quart. Joum. Micr. Soc, xlix. (1905) pp. 231-82 (3 pis. and 11 figs.). 

 + Arbeit. Zool. Inst. Univ. Wien, xvi. (1905) pp. 99-118 (4 pis.). 



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