1895. NOTES AND COMMENTS. 235 



be found lying in or about the peripheral chambers ot the parent. 

 (5) Under certain circumstances active zoospores are produced by 

 Foraminifera. It therefore appears (says Mr. Lister) that we may 

 safely conclude that the microspheric and megalospheric forms are 

 distinct from their origin. What, then, is their relationship ? When 

 two forms of a species are met with in animals or plants they generally 

 either belong to different sexes or they are members of a cycle of 

 recurring generations. The hypothesis that the two forms of the 

 Foraminifera represent the two sexes appears to be disproved by the 

 fact that in Orbital ites complanata, Lam., both megalospheric and micro- 

 spheric forms are found with the young of the megalospheric form 

 (primitive discs) in their brood chambers. Other genera furnish 

 analogous though less complete evidence. Hence it is impossible to 

 regard either form as male. We turn, then, to the other hypothesis, 

 namely, that the two forms are members of a recurring cycle of 

 generations. 



Mr. Lister goes on to show that in the reproduction of the micro- 

 spheric form the whole of the protoplasm of the parent is divided 

 into the young, and that these all belong to one form, the megalo- 

 spheric. The fact that the whole of the protoplasm of the parent 

 is used in the production of the young, and that these are all of 

 one form, supports the view that the two forms of the Foraminifera 

 belong to different generations. A fuller account of the process of 

 reproduction is promised by Mr. Lister in a further paper, which 

 we await with great interest. 



The Structure of Heliopova. 



Mr. G. C. Bourne's communication to the Royal Society upon 

 Heliopova has now been published (July, 1895), ^^"^ worthily maintains 

 the Oxford traditions of the study of Ccelenterates inaugurated by 

 Moseley. Professor Moseley himself made a notable contribution to 

 our knowledge of Heliopova ; but recent advances in knowledge of 

 other alcyonarians made a re-examination advisable. Indeed, it was 

 Moseley who, before his death, urged Mr. Bourne to undertake the 

 investigation. The work was done in the Linacre Laboratory at 

 Oxford upon Moseley's original material, with the addition of 

 collections made by Mr. Bourne at Diego Garcia, Professor Hickson 

 in Celebes, and Professor Haddon in the Torres Straits. 



The chief point of general interest relates to the origin of the 

 skeleton. By careful examination of young growing points Mr. 

 Bourne was able to make out that, as G. von Koch suggested, the 

 skeleton is truly ectodermal. The mesogloea, or gelatinous middle 

 layer, is formed by ectoderm cells, which either gradually become 

 gelatinous at their internal edges, or losing continuity with the 

 external layer migrate inwards, and first becoming surrounded by a 

 layer of discharged gelatinous material, ' melt' away into mesogloea. 



