Allman [I], 1 pl.
2) and Cladonema (Allman [I], pl.
Xvii.), and in Clavatella each whorl consists regularly of eight (Allman, loc. cit.
Knobbed at the extremity, as in Coryne (see Allman, loc. cit.
Iv.); (3) branched, a rare form in the polyp, but seen in Cladocoryne (see Allman, loc. cit.
The hypostome of the hydropolyp may be small, or, on the other hand, as in Eudendrium (Allman, loc. cit.
(After Allman.) sensory, contractile and pro tective in function.
(After Allman.) logy as the monopodial or racemose, and the sympodial or cymose types respectively; each is characteristic of one of the two sub-orders of the Hydroidea, the Gymnoblastea and Calyptoblastea.
(From Lubbock, after Allman.) by the founder proceeds to grow and to bud in the same way as the founder did, producing a side branch of the main stem.
This is the case in Syncoryne mirabilis (Allman , p. 278) and in Campanularia volubilis; in the latter, free medusae are produced in summer, gonophores in winter (Duplessis ).
Allman and A.
Allman, however, regarded this type of gonad as equivalent to a sporosac, and considered the medusa bearing them as a non-sexual organism, a " blastocheme " as he termed it, producing by budding medusoid gonophores.
In classifying methods of generation it is usual to make use of the sexual or non-sexual nature of the reproduction as a primary difference, but a more scientific classification is afforded by the distinction between tissue-cells After Allman, Gymnoblastic Hydroids, by permission of the Council of the Ray Society.
Similarly in Schizocladium portions of the hydrocaulus are cut off to form so-called " spores," which grow into new individuals (see Allman ).
Allman  put forward a more detailed view, which was as follows.
Apart from the weighty arguments which the development furnishes against the theories of Allman and Mechnikov, it may be pointed out that neither hypothesis gives a satisfactory explanation of a structure universally present in medusae of whatever class, namely the endoderm-lamella, discovered by the brothers O.
(After Allman.) Hydrocaulus (stem).
An apparent, but not real, exception is Halecium halecinum, in which the blastostyle is produced from the side of a nutritive polyp, and both are enclosed in a common theca without a partition between them (Allman  p. 50, fig.
Numerous medusae are budded successively within the gonotheca and set free; they swim off and mature in the open sea (Allman , p. 48, figs.
Medusae, so-called " meconidia," are budded but not liberated; each in turn, when it reaches sexual maturity, is protruded from the gonotheca by elongation of the stalk, and sets free the embryos, after which it withers and is replaced by another (Allman , p. 57, fig.
(Allman , pp. 50, 51, figs., 21-24;, Weismann , p. 170, pl.
(After Allman.) FIG.
In this sub-order have received Such are the " snake-like zoids " and as such are generally inter 4"0 ' 'Y p P After Allman, Gymnoblastic Hydroids, by permission of the council of the Ray Society.
After Allman, Gymnoblastic Hydroids, by permission of the council of the Ray Society.
Each corbula contains a central row of blastostyles enclosed and protected by lateral rows of branches representing stunted buds (Allman , p. 60, fig.
Ptychogastria Allman (=Pectyllis), a deep-sea form.
Allman, on the other hand, referred Limnocodium to the Leptomedusae.
(After Allman.) n, Pneumatocyst.
Allman, " A Monograph of the Gymnoblastic or Tubularian Hydroids," Ray Society (1871-1872); 2.
Allman, Greek Geometry from Thales to Euclid (1889); Florian Cajori, History of Mathematics (New York, 1894); M.
Van Beneden, Claparede, and Allman, who during the 19th century approached the study of the lower marine organisms in the same spirit as that in which Trembley and Schaffer in the 18th century, and Swammerdam in the 17th, gave themselves to the study of the minute fresh-water forms of animal life.
Gymnolaemata (Allman).- Lophophore circular, with no epistome.
The ancestrula (After Allman.) inaugurates a process of budding, conFIG.
This tissue is continuous from zooecium to zooecium (After Allman.) FIG.
(I) Allman, "Monogr.
Allman, "A Monograph of the Gymnoblastic or Tubularian Hydroids," Ray.
De la Soc ., &c., a Bordeaux; Allman, in Hermathena.
Allman, " Greek Geometry from Thales to Euclid," Hermathena, No.
The scyphistoma of Nausithoe forms a branching network which grows in the sponge Esperella and forms the colonial polypoid organism named by Schulze Spongicola fistularis, by Allman Stephanoscyphus mirabilis.