234 SUMMARY OF CURRENT RESEARCHES RELATING TO 



minutely punctate appearance, due to the presence of an immense 

 number of shallow pits ; each of these is the imprint of one of the large 

 epithelial cells of the embryo-capsule. The outer layer of the embryo 

 consists of rather large, closely-packed cells, inclosing a mass of clear, 

 transparent, jelly-like substance, in which immense numbers of amceboid 

 wandering cells are imbedded. The ectoderm consists of a single layer 

 of large sac- or flask -shaped cells, the neck of which is on the outer side 

 of the embrjo; the swollen portion projects inwards into the gelatinous 

 intercellular substance, and from its inner extremity frequently sends 

 out a few very short, slender, pseudopodial processes. 



The unusual length of time during which the embryo remains within 

 the mother sponge, and the great size to which it attains, necessitate 

 some special arrangement whereby it may be nourished; Mr. Dendy 

 believes that the investing epithelium has the function of nourishing the 

 embryo, absorption of nutriment being effected through the elongated 

 necks of some of the ectodermal cells. 



Within the ectodermal layer the embryo consists of a clear, jelly-like 

 matrix, in which there are numerous large amoeboid cells. These appear 

 to be simply ectodermal cells which have wandered into the central 

 jelly ; many of them become rounded, and so arranged as to give rise to 

 hollow chambers, lined by small spherical cells ; these cavities the 

 author regards as young flagellated chambers. Coincidently with the 

 formation of these a slit-like invagination appears on the surface of 

 the sponge, and it is around this that the chambers are formed. The 

 invagination is probably the commencement of a communication between 

 the chambers and the exterior ; but, unfortunately, it has not yet been 

 possible to trace the development further. 



It is not yet known how the embryos of Stelospongus escape from 

 the parent ; they may, as they increase in size, rupture the walls of the 

 oscular tubes near which they lie, when they would be forcibly ejected 

 with the outgoing stream of water ; or the sponge may die down in the 

 winter, and the embryos be released by the decay of the maternal 

 tissues. 



Protozoa. 



Biitschli's ' Protozoa.'* — Prof. Biitschli continues his general ac- 

 count of the organization of the ciliate Infusoria, and devotes a large 

 portion of the lately published parts to a history of the nuclei ; the 

 membranous investments are also described, and the processes of repro- 

 duction are begun, though not disposed of. 



Infusorial! Fauna of the Bay of KieLj — Prof. K. Mobius com- 

 mences his account of the Infusoria of the Bay of Kiel with a description 

 of Euplotes harpa ; various corrections are made in Stein's account of 

 this species. In addition to reproduction by transverse fission, a special 

 mode of gemmation after encystation was observed. In the latter mode 

 the creature rolls itself up, the cilia cease to beat, and the body becomes 

 surrounded by a delicate cyst ; granules appear in the ectoplasm which 

 refract the light strongly. The contractile vacuole grows considerably 

 and divides into smaller vacuoles ; these continually alter in form and 

 size and make their way into the protoplasm. Opposite the pectinellae 



* Bronn's Klassen u. Ordnungen, i. Protozoa (1888) pp. 1489-1584 (pis. 

 Ixxii.-v.). t Arch. f. Naturgesch., liv, (1888) pp. 81-116 (7 pis.). 



