No. 3.] DEVELOPMENT OF MARINE SPONGES. 365 
coast) have demonstrated that small pieces or cuttings of the 
commercial sponge have the ability to reproduce the entire 
organism. Cuttings from Tedania, which were suspended from 
mangrove roots in one of the “sounds” of Green Turtle Cay, 
grew very perceptibly in a month. 
In Tethya and Tetilla (Selenka 29, Desz6 3, 4) external 
buds are produced in a curious way. The buds consist of a 
solid mass of cells, and are formed in the peripheral region of 
the mother beneath the skin. As they mature they are 
gradually pushed out of the body along the spicules of the 
mother, until their only connection with the parent is through 
a slender stalk made up chiefly of these spicules. The bud 
then drops off. Deszd’s account of the early formation of 
these structures is extremely interesting, although his recorded 
facts scarcely seem to warrant his inferences. According to 
Deszé, the bud or gemmule is derived from a single cell, 
which undergoes a segmentation, and growing all the while 
gives rise to a solid morula. By the time the original cell has 
divided into four, a differentiation of “germ layers” takes 
place: one of the four cells constitutes the entoderm, the 
remaining three the ectoderm. The ectoderm then grows 
entirely round the entoderm cell. Cell multiplication con- 
tinues, the primary entoderm cell producing a solid mass of 
entoderm, surrounded by a single layer of ectoderm cells. 
The latter layer then splits off from its inner surface a layer 
of mesoderm, and itself gives rise to the external epithelium 
of the mature bud and to a stratum of tissue just beneath the 
epithelium, in which small asters (spicules) are developed. 
Deszo’s interpretation of certain cells as constituting distinct 
germ layers, is not very strongly supported by his figures. 
Vosmaer’s criticism in regard to this point may be given: “ Es 
ist wohl klar dass fiir die Deutungen der Zellen, wie sie Deszo 
vornimmt, kein Grund vorliegt”’ (Bronn’s Class. und Ordnung, 
p. 427). Deszé points out the importance, from a biological 
standpoint, of the discovery of germ layers in a non-sexually 
produced embryo, and calls to mind a similar discovery by 
Oscar Schmidt in the developing buds of Loxosoma. Schmidt’s 
account of the development of the Loxosoma buds (23, 24), 
