-134 SUMMARY OF CURRENT RESEARCHES RELATING TO 



but towards tlic base they become more transparent and similar, and in 

 the branching tubes they become indistinguishable from those of tho 

 reproductive organs. 



In early stages of the growth of new buds the endoderm is seen to 

 be derived from tho cells of the reproductive organs, and, when the 

 buds are formed, the blastostyles are nourished at the expense of the 

 tissue of the reproductive organs of the medusa. 



Wo seem hero to havo to do with a peculiarly modified process of 

 gemmation, and not with paedogenetic phenomena, as is probably the 

 case with the " sporogencsis " observed by Metschnikoff in Cunina. 



Anatomy of Madreporaria.* — Dr. G. H. Fowler gives an account of 

 the structure of Madracis asperula, Amphihelia ramea, Stephanophyllia 

 formosissima, Sphenotrochus rubescens, Stephanaria planipora, Pocillopora 

 nobilis, and Seriatopora tenuicornis. He thinks there is evidence that 

 the law that the body-wall, when present, is supported in acoenenchy- 

 matous forms upon peripheral lamellae of the mesenteries, and in 

 coenenchymatous species upon the echinulations of the coenenchyme, 

 requires modification. The two methods of support may coexist in a 

 coenenchymatous form (Madracis), and to a certain extent in an accenen- 

 chymatous (Amphihelia) ; the body-wall of acoenenchymatous species 

 may rest, either mainly (Amphihelia), or entirely (Stephanophyllia) on 

 pseudocostre ; in Sphenotrochus it rests on pseudocostae and true costae. 

 These apparent exceptions to the law may be due to exceptional condi- 

 tions, of which we are at present ignorant. 



The ultimate attachment of the polyp to the corallum consists, in 

 many genera, of a series of laminated offsets of mesogloea in the neigh- 

 bourhood of the mesentery ; these are the structures which have been 

 previously described as calicoblastic in function. In Sphenotrochus a 

 sphincter muscle, comparable to the " Eotteken's muscle " of the Hexac- 

 tiniae, may be found in the region of the mouth-disc. In the same form 

 follicle-cells, which are perhaps immigrants from the endoderm, may 

 surround the ripening ovum as it lies in its mesogloeal capsule. Stepha- 

 naria appears to be distinctly degenerate, owing to the low develop- 

 ment of the mesenterial filament, and the slight definition of the 

 boundaries of the polyps which compose the colony; the individuality 

 of the several polyps is, indeed, hardly more marked than in a Poriferan 

 colony. 



Development of Mancinia areolata.f — Mr. H. V. Wilson gives an 

 abstract of his observations on Mancinia areolata, a common Astraeid 

 coral in the Bahamas, and allied to the well-known brain-coral. After 

 segmentation there is a blastosphere with a very large cavity, and tho 

 cells contain numerous vacuoles which are probably filled with a fluid 

 yolk ; the germinal layers are formed by delamination, which takes 

 place irregularly over the whole surface of the blastosphere. The 

 permanent endoderm is a single layer of cells except in the region of 

 the oesophagus, where it forms a solid mass which stretches from the 

 oesophagus to the external ectoderm. The " mesenterial filaments " are 

 found to be not the thickened edges of the mesenteries, but lobes of the 

 oesophageal ectoderm. To form the first mesentery the whole oesophagus 

 moves laterally towards the meridian of the future mesentery, until in 



* Quart. Journ. Micr. Sci., xxviii. (1888) pp. 413-28 (2 pis.). 

 f Johns-Hopkins Univ. Circulars, vii. (1S88) pp. 31-3. 



