ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 27 



Tvinicata. 



Morphology of Tunicata.* — Maynard M. Metcalf has examined an 

 extensive series of simple and compound Tunicates with special reference 

 to the intersiphonal organs and their significance. He describes tho 

 various forms which these organs assume in representatives of almost 

 all the families, and sums up as follows. The ciliated funnel (dorsal 

 tubercle) is present in all species of Tunicates (except rarely in Phallusia 

 mammillata), and receives innervating fibres from the brain ; but in some 

 cases these latter were made out only in connection with the duct in the 

 vicinity of the funnel. The funnel may receive the duct of the neural 

 gland, but this is not invariably the case, and it cannot be regarded as 

 merely the aperture of the gland. Anatomically the evidence as to the 

 sensory function of the funnel is complete, but the nature of the sense sub- 

 served is entirely obscure. The development of the ciliated funnel shows 

 that it is the modified neuropore. The neural gland in some form is 

 present in all species of Tunicates, but is absent from the Phorozooid 

 of Doliolum. It arises from the central neural tube, and the anterior 

 part of this tube forms its duct, usually opening by the modified neuro- 

 pore into the pharynx. The secretion of the gland originates by the 

 disintegration of cells proliferated from the endothelium of its wall. 

 There are great differences between the different species in the degree 

 of development of the gland and the character of its rapheal prolongation, 

 but there is no great variability within the limits of a species. In regard 

 to function the author's results are chiefly negative ; and while he favours 

 the suggestion that the gland is the homologue of the hypophysis of 

 Vertebrates, he considers that this suggestion has been too hastily 

 accepted as established, in view of the many difficulties which still 

 exist. 



In addition to the account of the intersiphonal organs, the paper 

 includes discussions on various other points. Among these may be 

 noticed the discovery that Salpa cylindrica is protandrous and not proto- 

 gynous like other species ; the confirmation of Brooks' description of the 

 granular bodies within the blastomeres of embryos of Salpa as ingested 

 follicular nuclei ; an account of the anatomy of Octacnemus patagoniensis ; 

 a description of a new species of Bostrichobranchus ; and so on. The 

 author dissents from Herdman's view that Octacnemus is related to Salpa, 

 and believes that it should be placed among the simple Ascidians near 

 the Clavelinidae. 



Magellan Ascidians.f — Dr. W. Michaelsen gives an account of a 

 rich collection of holosomatous Ascidians, including the new genus 

 Agnesia, from the Magellan and South-Georgian region. 



Follicular Cells of Salpa.J — Herr Todaro describes tho remarkable 

 way in which the follicular cells — which he calls trophic or lecithin 

 cells — become associated with the blastomeres, and multiply among 

 them, first by karyokinesis and then amitotically. The body composed 

 of blastomeres plus lecithin cells is hardly an embryo ; it is a special 



* Zool. Jahrb. (Abt. Anat.), xiii. (1900) pp. 495-602 (10 figs, and 7 pis.). 

 t Zoologica (Chun), Heft 31, Bd. xii. (1900) pp. 1-148 (3 pis.). 

 X Vera. Anat. Ges., xiv. Vers. ; in Anat. Anzeig., xviii. (1900) Erg. Hft., pp. 194- 

 202 (3 figs.). 



