ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 595 



part lacunar, and the flagellated chambers open directly into them. 

 TMere is, however, some evidence to show that flagellated chambers 

 with and others without special canaliculi may coexist in the same sponge. 

 Both genera are remarkable for the development of the fibrous tissue. 

 In Bidleia it is largely develoj)ed in the ectosome proper, and in the 

 wall of the oscular tube, where it is arranged in well-defined layers of 

 longitudinal and circular fibres. In QuasiUina it is almost entirely 

 absent from the ectosome proper, but is well developed in the wall of 

 the oscular tube, where it forms definite annular ridges in which the 

 close-packed fibres (myocytes) have a distinct, wavy outline. The mode 

 of occurrence of the fibrous tissue indicates that its function is a contrac- 

 tile one, or in other words, that the fibres are muscular fibres ; the 

 annular bands of fibres around the oscular tube of QuasiUina are probably 

 to be regarded as sphincter muscles. 



With regard to the origin of spicules Mr. Dendy now takes Prof. 

 Schulze's view that the polyactinal type of spicule is the primitive form 

 from which the monactinal type has been derived by abortion of the 

 rays. The swollen base or head of a typical Suberitid spicule, together 

 with the corresponding enlargement of the axial thread, indicates the 

 position where other rays were at one time united with that one which 

 now alone remains. In the typical Suberitidee and in Bidleia all rays 

 but one have disappeared, but their former presence is still indicated by 

 the head of the tylostylote spicules. In QuasiUina the spicules are still 

 more modified, and the head has, in most cases, disappeared. 



It is probable that the lacunar type of canal system, as it occurs in 

 the Monaxonida, with chambers opening directly into wide lacunse, is less 

 primitive than the canalicular type. 



Chromatology of Sponges.* — Dr. C. A. MacMunn, out of the twelve 

 species of British sponges examined, found ten to contain chlorophyll ; 

 Krukenberg and other observers have figured the dominant chlorophyll 

 band in eight others. Probably Krukenberg f used solutions which 

 were too dilute to show the remaining bands, or examined only thin 

 layers of the solutions. Lipochromes occur in nearly all sponges, and 

 a histohjematin in seven of the sponges examined. A pigment resembling 

 a floridine (a class of red pigments described by Krukenberg) occurs in 

 HalicJiondria rosea, in addition to chlorophyll, a histohsematin, and a 

 lipochrome. A uranidine (a class of yellow pigments also described by 

 Krukenberg), occurs in Grantia coriacea, in addition to chlorophyll and 

 a lipochrome. This uranidine, like Krukenberg's aplysinofulvin (one 

 of the five pigments of Aphjsina), and others of the same class was 

 changed by boiling to dark green. 



With regard to the chlorophyll present in so many sponges, it was 

 found to resemble plant chlorophyll very closely. The lipochrome 

 constituent or constituents, however, reacted differently from the lipo- 

 chrome constituents of plant chlorophyll, as it remained unchanged by 

 the action of iodine in iodide of potassium, and the fractional method did 

 not separate the chlorophyll constituents (Hansen's " chlorophyll-green " 

 and " chlorophyll-yellow ") so completely as in the case of plant 

 chlorophyll. In these two points it resembles enterochlorophyll, and 

 proves that the chlorophyll is of purely animal origin. Microscopic 



* Jottrn. of Physiol., ix. (1888) pp. 1-25. Cf. Journ. Chem. Soc. Lond., 1888, 

 Abstr., p£. 619-20. f ' Grrundziige einer vergleich. Physiol, der Farbstoife,' 1884. 



