512 SUMMARY OF CURRENT RESEARCHES RELATING TO 



plete but very delicate layer of fibrils, apparently comparable to the 

 muscular layer found in the corresponding position in the male. The 

 central polyhedral cells give rise to ova. There is, therefore, an 

 essential agreement between the developmental processes of the male 

 and female. 



The male products escape, by the rupturing of their investing 

 wall, into the muscular layer, where a passage is found for them ; the 

 ectoderm undergoes change and atrophy, and the spermatozoa make 

 their way out. The ectoderm of the female breaks off at a non- 

 ciliated region at the anterior end, and thus the ova escape. There is 

 another female form which seems to divide into two or three pieces, 

 and which is distinguished by being flattened, and not cylindrical. 



The females, when mature, appear to leave one host to swim in the 

 water and to enter another, and there is some reason to believe that 

 the cylindrical forms give rise to the males, while the flattened 

 forms would seem to be the parents of the females. These latter 

 possibly arise by parthenogenesis. 



The author promises a fuller paper, in which he will give more 

 details and full reasons for his belief that the Orthonectida belong to 

 Van Beneden's group of the Mesozoa, and he concludes with an ob- 

 jection to the application of the terms metamere or segment to these 

 creatures, as the segmentation is superficial, affecting only the ecto- 

 derm, and the number of segments does, it is allowed, vary. 



Eyes of Rotifers. — Eeferring to his note read at the June meeting 

 of the Society,* Mr. Badcock writes (July 17) : — " Yesterday for the 

 first time I discovered eyes in a group of adult Floscularia cornuta, 

 and saw them again very distinctly in Stephanoceros eichhornii. It 

 seems to me desirable to put on record the fact that the eyes are 

 found in the adult forms of Melicerta ringens, M. tyro or tubicularia, 

 Floscularia cornuta, and Stephanoceros eichhornii, in all of which the 

 eye is ignored in the usual descriptions and drawings. The eyes are 

 not readily seen, but I have had some very fine specimens, and 

 may be able eventually to demonstrate their existence in all the 

 forms in which they were supposed to have been lost." 



Echinodermata. 



Anatomy of Holothurians.f — E. Jourdan finds in the connective 

 tissue of the integument of these Echinodermata elements forming 

 a plexus; they are coloured grey by osmic acid, are rarely 

 isolated, and are very often united into bundles. They arise from 

 nerves which penetrate into and extend through the skin. The 

 fibres of this nervous plexus are accompanied by nuclei, which are 

 chiefly found at the points of interlacement of the fibres. These 

 fibres are very fine, slightly varicose, and accompanied by fatty granu- 

 lations. The nervous centres consist of fibres and cells. The latter 

 are frequently, though not always, unipolar. 



The muscular elements of Holothurians are made up of fibres 



* See this Journal, post, Proceedings. 



t Comptes Eendus, xciv. (1882) pp. 1206-8. 



